This glossary provides definitions for key terms in Stoic philosophy, including original Greek terminology with transliteration and pronunciation, as well as English and Latin terms commonly used in Stoic discourse. Terms from other philosophical schools (Platonic, Aristotelian, Epicurean, Skeptic) are included where Stoic philosophers adopted, adapted, or engaged with them. Cross-references within definitions indicate related entries.
Adiaphora [Greek]
ἀδιάφορα | ah-dee-AH-for-ah
Indifferent things. In Stoic ethics, matters that are neither intrinsically good nor evil, including health, wealth, reputation, pleasure, and pain. These externals have no bearing on virtue or vice and thus do not affect eudaimonia. Stoics further subdivide adiaphora into preferred indifferents (proēgmena), dispreferred indifferents (apoproēgmena), and absolute indifferents.
Aegritudo [Latin]
eye-gree-TOO-doh
Distress; grief; contraction of the soul. The Latin equivalent of the Greek lupē. One of the four generic passions in Stoic psychology, aegritudo arises from the false judgment that something bad is present. Unlike the other three passions, distress has no corresponding rational emotion (eupatheia), since the sage recognizes that nothing genuinely bad can befall the virtuous person.
Agathos [Greek]
ἀγαθός | ah-gah-THOS
Good. In Stoic ethics, the only true good is virtue (aretē). Unlike Aristotelian ethics, which admits external goods, Stoicism holds that moral excellence alone constitutes the good, making virtue both necessary and sufficient for happiness.
Agnoia [Greek]
ἄγνοια | AHG-noy-ah
Ignorance. The opposite of knowledge (epistēmē). For the Stoics, moral failure stems from ignorance of the true nature of good and evil. All vice is a form of agnoia, since no one willingly chooses what they genuinely understand to be harmful.
Aisthēsis [Greek]
αἴσθησις | EYE-sthay-sis
Sense perception. The physical process of receiving external stimuli through the sense organs, which then produces a phantasia (impression). The Stoics were empiricists who believed that all knowledge begins with aisthēsis.
Aitia [Greek]
αἰτία | eye-TEE-ah
Cause. Central to Stoic physics and logic. The Stoics developed a sophisticated causal theory distinguishing between sustaining causes (sunektikon aition), antecedent causes, and co-operating causes. All events are causally determined by the chain of fate (heimarmenē).
Akrasia [Greek]
ἀκρασία | ah-KRAH-see-ah
Weakness of will; incontinence. Acting against one’s better judgment. While Socrates and the Stoics denied true akrasia—holding that no one knowingly does wrong—Aristotle accepted it as a genuine psychological phenomenon. The Stoics explained apparent weakness of will as resulting from false judgments about the good.
Alētheia [Greek]
ἀλήθεια | ah-LAY-thay-ah
Truth; unconcealment. In Stoic logic, truth is a property of propositions (axiōmata) that accurately represent reality. The Stoics developed propositional logic and criteria for distinguishing true from false impressions.
Amor fati [Latin]
AH-mor FAH-tee
Love of fate. Though a Latin phrase popularized by Nietzsche, the concept originates in Stoic philosophy. It expresses wholehearted acceptance of everything that happens, viewing all events—including apparent misfortunes—as expressions of divine providence and cosmic reason. Marcus Aurelius and Epictetus both emphasize welcoming fate rather than merely tolerating it.
Anankē [Greek]
ἀνάγκη | ah-NAHN-kay
Necessity; compulsion. The inexorable force governing events in the cosmos. Related to but distinct from heimarmenē (fate); anankē emphasizes the binding, inescapable character of causal determination. In mythology, Anankē is personified as the goddess of necessity.
Andreia [Greek]
ἀνδρεία | ahn-DRAY-ah
Courage; manliness. One of the four cardinal virtues in Greek ethics, alongside wisdom (sophia/phronēsis), justice (dikaiosynē), and temperance (sōphrosynē). For the Stoics, courage is knowledge of what is truly worth fearing (only vice) and not fearing (everything else, including death).
Anthrōpos [Greek]
ἄνθρωπος | AHN-throh-pos
Human being. Epictetus uses this term to express an ethical ideal: to act as a true human being means to fulfill our rational nature and live according to virtue. The question ‘What does it mean to be an anthrōpos?’ is central to Stoic ethics, answered by reference to our capacity for reason and our membership in the cosmopolis.
Apatheia [Greek]
ἀπάθεια | ah-PAH-thay-ah
Freedom from passion; equanimity. Not emotional numbness but liberation from destructive emotions (pathē) that arise from false judgments. The Stoic sage achieves apatheia by eliminating irrational impulses while cultivating rational emotions (eupatheiai) such as joy, caution, and reasonable wish.
Aphormē [Greek]
ἀφορμή | ah-for-MAY
Negative impulse; aversion; disinclination. The counterpart to hormē (positive impulse). In Stoic psychology, aphormē is the movement away from something perceived as harmful or undesirable. Wise aphormē targets only genuine evils (vice), not apparent evils (externals).
Apokatastasis [Greek]
ἀποκατάστασις | ah-poh-kah-TAH-stah-sis
Restoration; reconstitution. The return of the cosmos to its original state following ekpyrōsis (conflagration). In Stoic cosmology, the universe undergoes eternal recurrence: periodic destruction by fire followed by complete restoration of the same world order.
Apoproēgmenon [Greek]
ἀποπροηγμένον | ah-poh-pro-ayg-MEH-non
Dispreferred indifferent. Within the class of adiaphora, those things contrary to nature that we rationally avoid—such as illness, poverty, or disgrace—though they remain morally neutral. Opposite of proēgmenon (preferred indifferent).
Archē [Greek]
ἀρχή | ar-KAY
First principle; beginning; origin; ruling power. In Stoic physics, archē refers to the active principle (God, logos, pneuma) that shapes and governs matter. Pre-Socratic philosophers used archē to denote the fundamental substance underlying all reality.
Aretē [Greek]
ἀρετή | ah-reh-TAY
Virtue; excellence; optimal functioning. The supreme good in Stoic ethics and the only thing truly valuable. Aretē is unified: all virtues are aspects of a single disposition of rational wisdom. Virtue is knowledge of how to live, expressed in four forms: wisdom (sophia/phronēsis), justice (dikaiosynē), courage (andreia), and temperance (sōphrosynē).
Askēsis [Greek]
ἄσκησις | AHS-kay-sis
Exercise; training; practice. The disciplined practice required to internalize Stoic principles. Includes mental exercises (meditation, self-examination), physical discipline (enduring hardship), and practical training (responding properly to impressions). Related to the three Stoic disciplines.
Assent [English]
See Sunkatathesis. The mental act of affirming or accepting an impression (phantasia) as true. Assent is within our control and constitutes the locus of moral responsibility. Withholding assent from unclear or false impressions is central to Stoic epistemology and ethics.
Ataraxia [Greek]
ἀταραξία | ah-tah-rahk-SEE-ah
Tranquility; freedom from disturbance. A key goal in Hellenistic philosophy, especially prominent in Epicureanism and Pyrrhonian Skepticism. The Stoics acknowledged ataraxia as a consequence of virtue but emphasized apatheia (freedom from passion) and eudaimonia (flourishing) as primary aims.
Autarkeia [Greek]
αὐτάρκεια | ow-TAR-kay-ah
Self-sufficiency. The ideal of needing nothing external for happiness. The Stoic sage possesses autarkeia because virtue—the only good—depends entirely on one’s own rational choices. Derived from the Cynic tradition and Socratic teaching that the good person cannot be harmed.
Axiōma [Greek]
ἀξίωμα | ahk-see-OH-mah
Proposition; assertible. In Stoic logic, a complete lekton (meaning) that is either true or false. The Stoics developed propositional logic analyzing the logical relationships between axiōmata, including conditionals, conjunctions, and disjunctions.
Boulēsis [Greek]
βούλησις | BOO-lay-sis
Wish; rational wanting; reasonable desire. One of the three eupatheiai (good emotions) experienced by the Stoic sage. Boulēsis is the rational counterpart to the passion epithumia (appetite/lust). It represents a measured desire directed toward genuine goods—namely virtue—rather than the excessive craving for indifferents that characterizes passion.
Chara [Greek]
χαρά | kha-RAH
Joy; rational elation. One of the three eupatheiai (good emotions) available to the sage. Chara is the rational counterpart to the passion hēdonē (pleasure). It arises from the correct judgment that something genuinely good is present—specifically, one’s own virtue or virtuous activity. Unlike irrational pleasure, chara is stable and consistent with wisdom.
Compatibilism [English]
The philosophical position that determinism and moral choice are compatible. The Stoics held that all events—including human actions—are causally necessitated by fate (heimarmenē), yet maintained that our choices remain genuinely “up to us” (“eph’ hēmin”). This is possible because what matters for responsibility is not exemption from causal determination but that actions flow from our own rational nature (prohairesis). The metaphor of the dog tied to a cart illustrates the point: the dog will move with the cart regardless, but can choose to follow willingly or be dragged.
Cosmopolitanism [English]
The doctrine that all human beings are citizens of a single world community (kosmopolitēs = ‘citizen of the cosmos’). Originating with the Cynic Diogenes and developed by the Stoics, cosmopolitanism holds that our primary allegiance is to humanity as a whole, transcending local attachments to city, nation, or ethnicity.
Cosmos [Greek]
κόσμος | KOZ-mos
World-order; universe; ornament. The Stoics conceived the cosmos as a single, living, rational organism pervaded by divine logos/pneuma. The cosmos is finite, spherical, and surrounded by infinite void. ‘Kosmos’ also means ‘order’ or ‘adornment,’ reflecting the beauty and rationality of the universe.
Daimōn [Greek]
δαίμων | DYE-mohn
Divine spirit; inner genius; guiding spirit. In Stoic thought, the daimōn is the rational soul or hegemonikon—a fragment of divine reason dwelling within each person. Epictetus speaks of keeping one’s daimōn in good condition. Socrates famously referred to his daimonion as a divine sign.
Determinism [English]
The doctrine that all events are necessitated by prior causes according to natural law. The Stoics held a thoroughgoing causal determinism: every event, including human actions, follows necessarily from antecedent conditions. This coexists with moral responsibility because our assent to impressions remains ‘up to us’ in the relevant sense.
Diairesis [Greek]
διαίρεσις | dye-EYE-reh-sis
Division; distinction; analysis. The logical and psychological practice of distinguishing what is within our power (“eph’ hēmin”) from what is not. Epictetus makes diairesis foundational to his teaching. Also refers to logical division of genera into species.
Diaphoron [Greek]
διάφορον | dee-AH-for-on
Difference; different. Used to describe the relative value or ‘distinction’ between adiaphora (indifferent things). While all indifferents are morally neutral, some possess a diaphoron that makes them ‘preferred’ (proēgmena) over others because they align with our natural constitution.
Diathesis [Greek]
διάθεσις | dee-AH-theh-sis
Disposition; stable condition. A form of hexis (state) that does not admit of degrees—it is either fully present or absent, like the straightness of a rod. Virtues and vices are diatheseis: one either has complete virtue or lacks it entirely. This explains the Stoic paradox that all sages are equally wise and all non-sages equally foolish.
Dichotomy of Control [English]
The fundamental Stoic distinction between things that are ‘up to us’ (“eph’ hēmin”) and things that are not. Epictetus opens the Enchiridion with this teaching: our judgments, impulses, desires, and aversions are within our control; our bodies, reputations, possessions, and external circumstances are not. Freedom and happiness depend on focusing exclusively on what is within our power.
Dikaiosynē [Greek]
δικαιοσύνη | dee-kye-oh-SOO-nay
Justice; righteousness. One of the four cardinal virtues. For the Stoics, justice is the knowledge of how to distribute and deal fairly with others. It grounds our obligations to fellow human beings and connects to cosmopolitanism—the recognition of our membership in the universal community of rational beings.
Discipline of Action [English]
One of three Stoic disciplines. Corresponds to the virtue of justice and the topic of appropriate actions (kathēkonta). Governs how we act in the world, emphasizing service to others, social duties, and acting with the ‘reserve clause’ (hupexairesis) that acknowledges outcomes are not fully within our control.
Discipline of Assent [English]
One of three Stoic disciplines. Corresponds to the virtue of wisdom and the field of logic. Governs our judgments by training us to examine impressions before assenting, distinguish fact from interpretation, and avoid hasty or false beliefs.
Discipline of Desire [English]
One of three Stoic disciplines. Corresponds to the virtue of temperance and the field of physics. Governs our desires and aversions by aligning them with nature and fate. We should desire only virtue and be averse only to vice, accepting all externals with equanimity.
Dogma [Greek]
δόγμα | DOHG-mah
Belief; doctrine; decree. In Stoic psychology, our dogmata (beliefs) shape our emotional responses. Passions arise from false beliefs about what is good and evil. Philosophical therapy involves examining and correcting our dogmata. Marcus Aurelius frequently reflects on the power of beliefs to determine experience.
Doxa [Greek]
δόξα | DOHK-sah
Opinion; belief; reputation. Distinguished from epistēmē (knowledge). For the Stoics, doxa can be either true or false but lacks the stable, systematic character of genuine knowledge. The sage has only epistēmē, never mere doxa. In ordinary usage, doxa also means reputation or glory.
Dynamis [Greek]
δύναμις | DOO-nah-mis
Power; capacity; potentiality. In Aristotelian metaphysics, dynamis contrasts with energeia (actuality). The Stoics, as materialists, rejected Aristotle’s potentiality-actuality distinction but retained the concept of power or capacity, especially regarding the active principle (logos/pneuma) that shapes matter.
Eidos [Greek]
εἶδος | AY-dohs
Form; appearance; species. Plato’s term for the eternal, immaterial Forms. The Stoics rejected Platonic metaphysics, holding that only bodies exist. They reinterpreted eidos as the immanent organizing principle within matter, identified with the logos or rational structure of things.
Eklektikon [Greek]
ἐκλεκτικόν | ek-lek-tee-KON
Selective faculty. The rational capacity to choose between impressions, accepting some and rejecting others. Essential to the Stoic account of moral agency. The eklektikon enables us to select appropriate actions and preferred indifferents according to reason.
Ekpyrōsis [Greek]
ἐκπύρωσις | ek-poo-ROH-sis
Conflagration; cosmic fire. The periodic destruction of the cosmos by fire, after which the universe reconstitutes itself in identical form (apokatastasis). This Stoic doctrine of eternal recurrence holds that the same events repeat infinitely across cosmic cycles.
Eleutheria [Greek]
ἐλευθερία | eh-lef-theh-REE-ah
Freedom; liberty. For the Stoics, true freedom is internal: the sage is free because nothing external can compel assent or disturb equanimity. Epictetus, himself a former slave, emphasized that genuine freedom consists in rational self-governance, not external conditions.
Empeiria [Greek]
ἐμπειρία | em-pay-REE-ah
Experience; practical knowledge gained through observation. While the Stoics valued empirical observation in physics, they distinguished empeiria from epistēmē (scientific knowledge), which requires systematic understanding of causes and principles.
Energeia [Greek]
ἐνέργεια | en-AIR-gay-ah
Activity; actuality; being-at-work. Aristotelian term for the realization of potential. While the Stoics rejected the potentiality-actuality framework, they emphasized active engagement with life. The virtuous life is characterized by constant rational activity.
Ennoia [Greek]
ἔννοια | EN-noy-ah
Conception; concept. While a prolepsis is a natural, innate preconception, an ennoia is a concept formed through deliberate instruction, abstract reasoning, or specific experience.
Eph’ hēmin [Greek]
ἐφ’ ἡμῖν | ef-hay-MEEN
‘Up to us’; within our power. The domain of our legitimate concern. Includes our judgments, impulses, desires, and aversions—everything depending on the use of our prohairesis (moral choice). Contrasts with ouk eph’ hēmin (not up to us): body, property, reputation, and all externals.
Epistēmē [Greek]
ἐπιστήμη | eh-pis-TAY-may
Knowledge; science; systematic understanding. Distinguished from mere true opinion (doxa). The Stoics defined epistēmē as katalēpsis (apprehension) that is stable and cannot be dislodged by argument. Only the sage possesses epistēmē; others have at best katalēpseis that fall short of systematic knowledge.
Ergon [Greek]
ἔργον | AIR-gon
Work; function; characteristic activity. Aristotle’s ‘function argument’ holds that human flourishing depends on fulfilling our ergon (rational activity). The Stoics adopted this framework: our ergon is to live according to reason, which means living virtuously and in accordance with nature.
Ethos [Greek]
ἦθος | AY-thos
Character; habit; customary behavior. Aristotle derived ‘ethical virtue’ from ethos, emphasizing that character is formed through practice. The Stoics stressed that character is constituted by our prohairesis (moral choice) and the judgments we habitually make.
Eudaimonia [Greek]
εὐδαιμονία | ev-dye-moh-NEE-ah
Happiness; flourishing; well-being; living well. The telos (goal) of human life according to all major Greek ethical schools. For the Stoics, eudaimonia consists in virtue alone—the excellent condition of the rational soul—and is unaffected by external circumstances. Literally: ‘having a good daimōn.’
Eulabeia [Greek]
εὐλάβεια | ev-LAH-bay-ah
Caution; rational wariness; discretion. One of the three eupatheiai (good emotions) experienced by the sage. Eulabeia is the rational counterpart to the passion phobos (fear). It represents appropriate concern about genuine evils—namely vice and moral failure—without the irrational disturbance that characterizes fear of indifferents like death or pain.
Eupatheia [Greek]
εὐπάθεια | ev-PAH-thay-ah
Good emotion; rational affect. The Stoics distinguished destructive passions (pathē) from three species of rational emotions available to the sage: chara (joy), boulēsis (rational wish), and eulabeia (caution). These arise from true judgments and are consistent with virtue.
Euroia [Greek]
εὐροία | ev-ROY-ah
Good flow; smooth flow of life. A Stoic description of happiness and the well-lived life. Euroia characterizes existence that proceeds unimpeded and unobstructed by the vicissitudes of fortune. The sage experiences euroia because nothing external can disturb the rational soul that desires only virtue and is averse only to vice.
Externals [English]
Things outside our control (ouk eph’ hēmin) that do not affect our virtue or character. Includes body, property, reputation, social status, relationships, health, pleasure, pain, life, and death. Externals are morally indifferent (adiaphora); only our responses to them have ethical significance.
Fate [English]
See Heimarmenē. The causal chain governing all events in the cosmos. The Stoics taught acceptance of fate as the expression of divine providence. The phrase ‘Ducunt volentem fata, nolentem trahunt‘ (Fate leads the willing and drags the unwilling) captures the Stoic attitude.
Free Will [English]
The capacity for self-determined action. The Stoics held a compatibilist position: human choices are causally determined yet remain ‘up to us’ because they flow from our own rational nature. Freedom consists not in exemption from causation but in rational self-governance through prohairesis.
Hamartia [Greek]
ἁμαρτία | hah-mar-TEE-ah
Error; mistake; missing the mark. In tragedy, the protagonist’s fatal flaw. For the Stoics, all wrongdoing is hamartia—a cognitive error based on false beliefs about good and evil. No one errs willingly; vice stems from ignorance.
Hegemonikon [Greek]
ἡγεμονικόν | hay-geh-moh-nee-KON
Ruling faculty; commanding element; rational center. The central, governing part of the soul located (for the Stoics) in the heart. All impressions are referred to the hegemonikon for judgment; it is the seat of reason, assent, impulse, and moral responsibility.
Heimarmenē [Greek]
εἱμαρμένη | hay-mar-MEH-nay
Fate; destiny. The causal chain linking all events according to divine reason. The Stoics identified heimarmenē with providence (pronoia), logos, and Zeus. Everything that happens is fated, but this does not eliminate moral responsibility since our assent remains ‘up to us’ within the causal order.
Hexis [Greek]
ἕξις | HEK-sis
State; habit; disposition. A stable condition of the soul produced by repeated actions. Virtues and vices are hexeis. Aristotle emphasized that virtues are acquired through practice; the Stoics agreed that philosophical training aims to establish the hexis of wisdom.
Hierocles’ Circles[English]
A Stoic visualization exercise used to practice oikeiōsis (appropriation/affiliation). It involves visualizing oneself at the center of concentric circles—representing family, neighbors, fellow citizens, and all of humanity—and mentally drawing the outer circles inward to treat strangers as kin.
Hormē [Greek]
ὁρμή | hor-MAY
Impulse; motivation; drive toward action. In Stoic psychology, hormē follows from assent to an impression that something is appropriate to pursue. Excessive or irrational hormē constitutes pathos (passion). The sage has only rational impulses aligned with virtue.
Hupexairesis [Greek]
ὑπεξαίρεσις | hoo-pek-SYE-reh-sis
Reserve clause; exception. The mental reservation added to every intention: ‘I will do X, if fate permits.’ This acknowledges that outcomes depend on factors beyond our control. Seneca’s ‘If nothing prevents it’ and Marcus Aurelius’s qualifications exemplify hupexairesis.
Hylē [Greek]
ὕλη | HOO-lay
Matter; material; wood. The passive principle in Stoic physics, contrasted with logos/pneuma (the active principle). Matter is eternal, ungenerated, and uncreated; it receives form from the active principle. The Stoics were materialists: only bodies (composed of matter) truly exist.
Hyparxis [Greek]
ὕπαρξις | HOO-par-ksis
Existence; subsistence; reality. The Stoics distinguished ‘something’ (ti) from ‘existent’ (huparxis). Only bodies exist; incorporeals (lekta, void, place, time) merely ‘subsist’ without full being. This ontological framework solved problems about the status of meanings and abstract entities.
Hypolēpsis [Greek]
ὑπόληψις | hoo-POH-layp-sis
Opinion; assumption; supposition. A belief or judgment about the nature of things. Epictetus frequently uses hypolēpsis interchangeably with dogma to denote the beliefs that shape our emotional responses. Since passions arise from false hypolēpseis about good and evil, philosophical therapy involves examining and correcting our underlying assumptions.
Hypomnemata [Greek]
ὑπομνήματα | hoo-pom-NAY-mah-tah
Notes; memoranda; personal notebooks. Records kept for philosophical self-examination and practice. Marcus Aurelius’s Meditations exemplify hypomnemata—private reflections written to oneself for spiritual exercise. The practice involves recording maxims, self-admonitions, and philosophical principles to internalize Stoic teachings through repeated reading and reflection.
Impression [English]
See Phantasia. A mental presentation or appearance received through sense perception or thought. The Stoics distinguished impressions from the assent we give them; examining impressions before assenting is central to the discipline of assent.
Indifferent [English]
See Adiaphora. Anything neither virtuous nor vicious, including health, wealth, pleasure, pain, life, and death. Indifferents are subdivided into preferred (kata phusin—according to nature), dispreferred (para phusin—contrary to nature), and absolute indifferents.
Inner Citadel [English]
A metaphor for the hegemonikon (ruling faculty) as an impregnable fortress. Drawn from Marcus Aurelius’s Meditations. The inner citadel represents the mind’s capacity to remain undisturbed regardless of external circumstances. No external event can breach it without our assent.
Internals [English]
Things within our control (eph’ hēmin): our judgments, values, intentions, desires, and aversions. The domain of virtue and vice. Only internals have moral significance; they constitute the sphere of human freedom and responsibility.
Judgment [English]
The mental act of evaluating impressions and assenting to propositions. In Stoic psychology, judgments are the proximate cause of emotions. Passions arise from false judgments (e.g., that external loss is bad); correcting judgments transforms emotional responses.
Kairos [Greek]
καιρός | kye-ROSS
Opportune moment; right time; due measure. The qualitative dimension of time, as opposed to chronos (quantitative time). Recognizing kairos—the appropriate moment for action—requires practical wisdom (phronēsis). The Stoics emphasized acting appropriately to circumstances.
Kakon [Greek]
κακόν | kah-KON
Evil; bad. For the Stoics, the only true evil is vice—defective character or irrational judgment. External misfortunes (poverty, illness, death) are not genuinely evil but morally indifferent. Evil resides solely in our use of impressions and prohairesis.
Kalon [Greek]
καλόν | kah-LON
Noble; beautiful; fine; honorable. The morally beautiful. For the Stoics, kalon and agathos (good) are equivalent: virtue is both good and beautiful. Kalon carries aesthetic connotations: virtuous action has an intrinsic beauty that makes it choiceworthy for its own sake.
Katalēpsis [Greek]
κατάληψις | kah-tah-LAY-psis
Apprehension; grasp; comprehension. Cognitive assent to a cataleptic (apprehensive) impression—one that could not be false. Katalēpsis occupies a middle ground between mere opinion and scientific knowledge. It forms the criterion of truth for the Stoics.
Kathēkon [Greek]
καθῆκον | kah-THAY-kon
Appropriate action; fitting action; proper function; duty. Actions in accordance with nature that can be rationally justified. Kathēkonta include self-preservation, caring for family, civic participation, and social obligations. Distinguished from katorthōmata (perfect actions), kathēkonta can be performed without perfect virtue.
Katorthōma [Greek]
κατόρθωμα | kah-TOR-thoh-mah
Perfect action; right action. An action performed with complete virtue—not just conforming to duty externally but arising from the sage’s perfected character. Only the sage performs katorthōmata; others perform kathēkonta (appropriate actions) without the internal perfection that virtue requires.
Kinēsis [Greek]
κίνησις | KEE-nay-sis
Motion; change; movement. In Stoic physics, all change results from the active principle (logos/pneuma) acting on matter. The Stoics distinguished various types of kinēsis: locomotion, alteration, growth, and diminution.
Koinai Ennoiai [Greek]
κοιναὶ ἔννοιαι | koy-NYE en-NOY-eye
Common notions; shared concepts. Universal preconceptions that develop naturally in all rational beings through experience. The Stoics held that certain basic concepts—such as ‘good,’ ‘just,’ and ‘god’—are common to all humanity and serve as criteria for judgment. Disagreements arise not from different common notions but from their misapplication to particular cases.
Kosmopolitēs [Greek]
κοσμοπολίτης | koz-moh-poh-LEE-tays
Citizen of the cosmos; world-citizen. The Stoic ideal of universal belonging. Diogenes the Cynic first declared himself a kosmopolitēs. The Stoics developed this into a systematic doctrine: all rational beings belong to a single universal community governed by natural law.
Laetitia [Latin]
lye-TEE-tee-ah
Pleasure; delight; elation. The Latin equivalent of the Greek hēdonē. One of the four generic passions in Stoic psychology as transmitted through Roman sources like Cicero and Seneca. Laetitia represents irrational elation over the supposed presence of something good, when the object is actually an indifferent. Distinguished from gaudium (rational joy).
Lekton [Greek]
λεκτόν | lek-TON
Sayable; meaning; sense. An incorporeal entity expressed in language but distinct from both words (sounds) and objects. Lekta include propositions (axiōmata), predicates, and other semantic entities. The Stoics pioneered philosophy of language through their theory of lekta.
Libido [Latin]
li-BEE-doh
Appetite; lust; desire. The Latin equivalent of the Greek epithumia. One of the four generic passions in Roman Stoic sources. Libido represents irrational craving for some future object falsely judged to be good. Seneca analyzes various species of libido, including anger (ira), which he treats extensively as a destructive passion requiring therapeutic intervention.
Living According to Nature [English]
The Stoic formula for the good life: homologoumenōs tē phusei zēn. This means living according to reason (our specific nature as humans), living in harmony with cosmic nature (the rational order of the universe), and acting appropriately to our circumstances and relationships.
Logos [Greek]
λόγος | LOH-gos
Reason; word; principle; account; proportion. A term with many meanings, central to Greek philosophy. For the Stoics, logos is the divine rational principle pervading and governing the cosmos—identified with God, Zeus, fate, providence, and pneuma. In us, logos is the capacity for rational thought that connects us to cosmic reason.
Logos Spermatikos [Greek]
λόγος σπερματικός | LOH-gos sper-mah-tee-KOSS
Seminal reason; generative principle; seed-logos. The rational, creative power inherent in the cosmos that contains the seeds (spermata) of all things that will develop. The Stoics conceived the universe as unfolding according to logoi spermatikoi—rational patterns embedded in matter by divine providence. Each individual thing develops according to its own spermatikos logos.
Lupē [Greek]
λύπη | loo-PAY
Distress; pain; grief; contraction. One of the four generic passions (pathē) in Stoic psychology. Lupē arises from the false judgment that something bad is present. Species include pity, envy, resentment, anguish, and sorrow. Uniquely among the four passions, lupē has no rational counterpart (eupatheia), since the sage recognizes that no genuine evil can befall the virtuous.
Materialism [English]
The metaphysical doctrine that only bodies (matter) exist. The Stoics held that everything real—including souls, virtues, and God—is corporeal. Only four ‘incorporeals’ subsist without full existence: lekta (meanings), void, place, and time. This distinguishes Stoicism from Platonic dualism.
Melete [Greek]
μελέτη | meh-LEH-tay
Practice; meditation; exercise. Philosophical training through repeated rehearsal of doctrines and principles. Melete includes premeditating future difficulties, memorizing maxims, and mentally rehearsing proper responses to impressions. Essential to Stoic askēsis.
Memento mori [Latin]
meh-MEN-toh MOR-ee
‘Remember that you will die.’ A meditation practice for maintaining perspective and urgency. Marcus Aurelius frequently contemplates mortality; Epictetus advises keeping death before our eyes. Awareness of death clarifies what truly matters and motivates virtue.
Moral Progress [English]
See Prokopē. Advancement toward virtue and wisdom. The Stoics acknowledged that most people are not sages but can make progress through philosophical practice. Progress involves correcting false beliefs, weakening passions, and strengthening rational control.
Natural Law [English]
Universal moral principles grounded in cosmic reason. The Stoics held that divine logos establishes rational norms binding on all humanity. This concept profoundly influenced Roman jurisprudence, Christian ethics, and modern theories of human rights.
Nomos [Greek]
νόμος | NOH-mos
Law; custom; convention. Distinguished from phusis (nature). Greek thought debated whether values are natural or conventional. The Stoics argued that true law is natural law—the rational order of the cosmos—which grounds and transcends positive (human-made) law.
Nous [Greek]
νοῦς | NOOS
Mind; intellect; reason. The highest cognitive faculty. Aristotle distinguished nous from discursive reason (dianoia). The Stoics identified nous with logos and the hegemonikon—the rational ruling faculty that constitutes our essential nature and connects us to cosmic mind.
Oikeiōsis [Greek]
οἰκείωσις | oy-kay-OH-sis
Appropriation; affiliation; familiarization; orientation. The natural process by which living beings are drawn toward what preserves them and away from what harms them. Oikeiōsis begins with self-preservation, extends to family and community, and culminates in cosmopolitan identification with all rational beings.
Orexis [Greek]
ὄρεξις | OH-rek-sis
Desire; reaching; appetite for something perceived as good. The general impulse toward objects of pursuit, contrasted with ekklisis (aversion). In Stoic psychology, orexis should properly be directed only toward virtue—the sole genuine good. Misdirected orexis, aimed at indifferents, generates the passion of epithumia. Epictetus emphasizes training orexis as fundamental to philosophical progress.
Orthos logos [Greek]
ὀρθὸς λόγος | or-THOS LOH-gos
Right reason; correct reasoning. The rational norm guiding virtuous action. Living according to orthos logos means making judgments and choices that accord with the rational order of nature. The sage’s hegemonikon operates consistently with orthos logos.
Ousia [Greek]
οὐσία | oo-SEE-ah
Being; substance; essence. Aristotle’s term for the primary category of existence. The Stoics reinterpreted ousia in materialist terms: the underlying substrate (hupokeimenon) that receives qualities. God/logos and matter are the two aspects of ousia.
Paideia [Greek]
παιδεία | pye-DAY-ah
Education; culture; formation. The process of cultivating character and intellect. Stoic paideia involves logical training, ethical teaching, and physical understanding—comprehensive formation aimed at producing the wise person (sophos).
Palingenesia [Greek]
παλιγγενεσία | pah-lin-geh-neh-SEE-ah
Regeneration; rebirth. Specifically refers to the rebirth of the cosmos into a new cycle after its periodic destruction by fire (ekpyrōsis). It is the process by which the universe reconstitutes itself in its identical form (apokatastasis).
Paschon [Greek]
πάσχον | PAH-skhon
The passive principle; that which is acted upon. In Stoic physics, paschon refers to inert matter (hylē) that receives form and motion from the active principle (poioun/logos/pneuma). The two principles are inseparable: matter never exists without being shaped by reason, and reason always inheres in matter. Together they constitute the corporeal cosmos.
Passion [English]
See Pathos. An irrational, excessive impulse arising from false judgment. The Stoics classified four primary passions: distress (lupē), fear (phobos), appetite (epithumia), and pleasure (hēdonē). Passions are psychic disturbances to be eliminated through philosophical therapy.
Pathos [Greek]
πάθος | PAH-thos
Passion; emotion; suffering. An irrational impulse or ‘excessive impulse’ (pleonazousa hormē) arising from false judgment about good and evil. The four generic passē are distress, fear, appetite, and pleasure. Stoic therapy aims at eliminating pathē, not moderating them (contra Aristotle).
Phantasia [Greek]
φαντασία | fahn-tah-SEE-ah
Impression; appearance; representation. A modification of the soul produced by external objects (sensory impression) or internal thought. Phantasiai present content for potential assent. The sage tests impressions before assenting, distinguishing cataleptic (apprehensive) from non-cataleptic impressions.
Phantasia katalēptikē [Greek]
φαντασία καταληπτική | fahn-tah-SEE-ah kah-tah-layp-tee-KAY
Apprehensive impression; cataleptic impression. An impression arising from a real object, accurately representing it, and stamped with characteristics that could not belong to a false impression. Katalēptikē phantasiai guarantee truth and serve as the Stoic criterion of knowledge.
Phantastikon [Greek]
φανταστικόν | fahn-tahs-tee-KON
Imaginary presentation; mental image produced internally. Distinguished from phantasia (impression received from external objects), phantastikon refers to dreams, fantasies, and hallucinations generated by the mind’s manipulation of stored mental content. The Stoics emphasized distinguishing reliable katalēptikai phantasiai from deceptive phantastika that do not correspond to reality.
Phobos [Greek]
φόβος | FOH-boss
Fear; dread; irrational shrinking. One of the four generic passions (pathē) in Stoic psychology. Phobos arises from the false judgment that some future evil is approaching, when the anticipated object is actually an indifferent. Species include terror, hesitation, shame, panic, and agony. The rational counterpart is eulabeia (caution directed at genuine evils).
Phronēsis [Greek]
φρόνησις | FROH-nay-sis
Practical wisdom; prudence. The knowledge of what to do and what to avoid in particular circumstances. One of the four cardinal virtues. For the Stoics, phronēsis is the application of unified virtue to the domain of action. Aristotle distinguished phronēsis from sophia (theoretical wisdom).
Phusis [Greek]
φύσις | FOO-sis
Nature; growth; constitution. Both universal nature (the cosmic order governed by logos) and individual nature (one’s own rational constitution). ‘Living according to nature’ means harmonizing both: fulfilling one’s rational nature while accepting cosmic fate.
Pneuma [Greek]
πνεῦμα | PNYOO-mah
Breath; spirit; vital force. The active principle in Stoic physics, identified with logos, God, and fire mixed with air. Pneuma pervades all matter in varying degrees of tension (tonos), producing different levels of being: hexis (cohesion in objects), phusis (nature in plants), psychē (soul in animals), and logos (reason in humans).
Poioun [Greek]
ποιοῦν | poy-OON
The active principle; that which acts. In Stoic physics, poioun refers to God, logos, or pneuma—the rational, creative force that shapes and organizes matter (paschon). The active principle pervades all matter, providing cohesion to inanimate objects, life to plants, soul to animals, and reason to humans. It is corporeal, identified with an intelligent, fiery breath.
Preferred Indifferent [English]
See Proēgmenon. An indifferent thing ‘according to nature’ (kata phusin) that has rational grounds for selection, such as health, wealth, or reputation. Though not good (only virtue is good), preferred indifferents provide the material for appropriate action (kathēkon).
Premeditatio malorum [Latin]
preh-meh-dee-TAH-tee-oh mah-LOH-room
‘Premeditation of evils’; negative visualization. The practice of imagining possible misfortunes in advance. By rehearsing difficulties mentally, we reduce their power to disturb and prepare appropriate responses. Seneca recommends daily reflection on potential setbacks.
Proēgmenon [Greek]
προηγμένον | pro-ayg-MEH-non
Preferred indifferent. Within the class of adiaphora (indifferents), those things ‘according to nature’ (kata phusin) that have selective value: health, strength, wealth, reputation, pleasure. Rationally chosen when available, though never at the cost of virtue. Opposite of apoproēgmenon.
Prohairesis [Greek]
προαίρεσις | proh-HYE-reh-sis
Moral choice; will; rational volition; faculty of choice. The core of human selfhood and moral responsibility. Epictetus makes prohairesis central: it is entirely within our power and constitutes who we truly are. Prohairesis governs our use of impressions and determines our character.
Prokopē [Greek]
προκοπή | proh-koh-PAY
Progress; advancement. Moral and philosophical improvement toward wisdom. The Stoics recognized that most people are not sages but prokoptontes (progressors). Progress involves strengthening rational control, weakening passions, and correcting false beliefs through sustained practice.
Prokoptōn [Greek]
προκόπτων | proh-KOP-tohn
One making progress; a progressor. Someone advancing toward virtue without yet achieving the sage’s perfection. All non-sages who pursue philosophy are prokoptontes. Stoic practice is designed for progressors, acknowledging human imperfection while maintaining the ideal.
Prolepsis [Greek]
πρόληψις | PROH-layp-sis
Preconception. Innate, universal concepts (such as ‘the good’ or ‘the just’) that form naturally in all rational beings through repeated experiences. These ‘pre-formed’ ideas serve as the essential criteria for further reasoning and judgment (katalēpsis).
Pronoia [Greek]
πρόνοια | PROH-noy-ah
Providence; forethought. Divine rational governance of the cosmos. The Stoics identified pronoia with fate (heimarmenē), logos, and Zeus. Everything that happens occurs through providence for the good of the whole. Accepting providence means recognizing cosmic events as rationally ordered.
Prosochē [Greek]
προσοχή | proh-soh-KHAY
Attention; mindfulness; vigilance. Constant awareness of one’s mental states and impressions. Prosochē is foundational to Stoic practice: by attending to impressions before assenting, we can avoid false judgments and maintain rational control. Related to the discipline of assent.
Psychē [Greek]
ψυχή | psoo-KHAY
Soul; life; mind. For the Stoics, psychē is corporeal—a breath of pneuma capable of receiving impressions and producing impulses. The human soul has eight parts: five senses, speech, reproduction, and the hegemonikon (ruling faculty). After death, souls persist for varying durations before dissolution.
Reserve Clause [English]
See Hupexairesis. The mental qualification attached to intentions: ‘fate willing’ or ‘if nothing prevents it.’ Acknowledges that outcomes depend on factors beyond our control. Proper intention aims at virtuous effort, not guaranteed results.
Sage [English]
See Sophos. The ideally wise person who has achieved perfect virtue. The sage has only true beliefs, experiences no pathē (passions), and possesses complete happiness. Though rare or perhaps non-existent, the sage serves as a normative ideal guiding moral progress.
Skopos [Greek]
σκοπός | skoh-POSS
The target or objective. In Stoic ethics, it is strictly distinguished from the telos (ultimate goal). In the ‘Archer’s Analogy,’ the skopos is hitting the external target (a preferred indifferent), whereas the telos is the internal excellence and virtue of the attempt itself.
Sophia [Greek]
σοφία | soh-FEE-ah
Wisdom; knowledge. The supreme virtue encompassing all others. For the Stoics, wisdom is knowledge of divine and human affairs—systematic understanding of how to live. The sage (sophos) possesses sophia completely; others have at best partial wisdom.
Sophos [Greek]
σοφός | soh-FOSS
Sage; wise person. The person of perfect virtue who has achieved the telos of human life. The Stoic sage is free, happy, and undisturbed regardless of external circumstances. All sages are equally wise; there are no degrees of wisdom (only degrees of progress toward it).
Sōphrosynē [Greek]
σωφροσύνη | soh-froh-SOO-nay
Temperance; moderation; self-control; sound-mindedness. One of the four cardinal virtues. For the Stoics, sōphrosynē is knowledge of what to choose and avoid regarding impulses—mastery over desire and appetite through rational understanding.
Summum bonum [Latin]
SOOM-oom BOH-noom
‘Highest good.’ The ultimate aim of human life that all other goods serve. For the Stoics, the summum bonum is virtue (aretē), which is identical with living according to nature and reason. All genuine goods reduce to virtue; all genuine evils reduce to vice.
Sunkatathesis [Greek]
συγκατάθεσις | soong-kah-TAH-theh-sis
Assent; agreement; acceptance. The mental act of accepting an impression as true. Sunkatathesis is entirely within our power and constitutes the locus of moral responsibility. The sage assents only to cataleptic (apprehensive) impressions; withholding assent from unclear impressions avoids error.
Sympatheia [Greek]
συμπάθεια | soom-PAH-thay-ah
Cosmic sympathy; interconnection. The mutual affection and causal connection between all parts of the cosmos. Because the universe is a living organism, events in one part affect all others. Sympatheia grounds divination and explains cosmic harmony.
Syneidēsis [Greek]
συνείδησις | soo-NAY-day-sis
Conscience; consciousness; moral awareness. The inner witness to one’s actions and intentions. The Stoics recognized syneidēsis as the voice of reason judging our conduct. Marcus Aurelius emphasizes living so as to have no cause for self-reproach.
Techne [Greek]
τέχνη | TEKH-nay
Art; craft; skill; systematic knowledge for production. Distinguished from epistēmē (theoretical knowledge) by its practical aim. The Stoics conceived ethics as an art of living (techne tou biou)—systematic knowledge applied to practical conduct.
Telos [Greek]
τέλος | TEH-loss
End; goal; purpose; completion. The ultimate aim toward which all action tends. For the Stoics, the telos of human life is eudaimonia (flourishing), achieved through virtue alone. The telos provides the criterion for evaluating all choices and actions.
Theōria [Greek]
θεωρία | theh-oh-REE-ah
Contemplation; theoretical study; observation. For Aristotle, the highest form of activity. The Stoics valued theoretical understanding of physics as preparation for ethics: knowledge of cosmic nature informs how to live according to nature.
Theos [Greek]
θεός | theh-OSS
God; the divine. The Stoics identified God with the active principle (poioun), logos, pneuma, Zeus, fate, providence, and nature. Stoic theology is pantheistic and materialist: God is not separate from the cosmos but is the rational, ordering principle immanent in all matter. The cosmos itself is a living, divine organism. Individual souls are fragments of the divine logos.
Tonos [Greek]
τόνος | TOH-nos
Tension; tone; vital force. The degree of pneuma‘s activity that determines the qualities of bodies. Higher tonos produces more complex beings: minimal tonos creates cohesion (hexis) in inanimate objects; greater tonos produces plant life (phusis), animal soul (psychē), and rational soul (logos).
Topoi [Greek]
τόποι | TOH-poy
‘Places’ or ‘Topics.’ This refers to the three traditional fields of Stoic study: Physics, Ethics, and Logic. These serve as the theoretical foundation for the three practical ‘Disciplines’ (Desire, Action, and Assent).
Tyche [Greek]
τύχη | TOO-khay
Fortune; chance; luck. What appears random from a limited perspective but is actually determined by fate. The Stoics denied genuine chance: tyche names human ignorance of causal necessity, not ontological indeterminacy. The sage is indifferent to tyche, finding security only in virtue.
Universal Reason [English]
See Logos. The divine rational principle governing the cosmos. All individual reason participates in universal reason. Living according to nature means bringing one’s individual logos into harmony with the cosmic logos.
View from Above [English]
A meditation technique imagining oneself rising above earthly concerns to view human affairs from a cosmic perspective. Marcus Aurelius frequently employs this exercise. From the cosmic vantage point, ordinary preoccupations appear trivial, while our connection to the whole becomes evident.
Virtue [English]
See Aretē. Excellence of character; the good condition of the soul. Virtue is the only true good and constitutes happiness (eudaimonia). The four cardinal virtues—wisdom, justice, courage, and temperance—are unified aspects of a single rational disposition.
Zoon [Greek]
ζῷον | ZOH-onLiving being; animal. The Stoics viewed the cosmos itself as a zoon—a living, rational organism. Human beings are zōa logika (rational animals), distinguished from other zōa by possessing logos. Our telos is to fulfill our nature as rational living beings.
Summary Statistics
| Total Terms | 151 |
| Greek Terms | 116 |
| English/Latin Terms | 35 |