ἀγαθόν, τό: the good; for the Stoics, virtue alone is good.
ἀδιάφορον, τό: an indifferent, something which is neither good nor evil in itself. Wealth and political office are examples. Indifferents do not contribute to the moral well-being of a person.
ἀπάθεια, ἡ: freedom from passion, which is a constituent of εὐδαιμονία.
ἄσκησις, ἡ: practice in evaluating your impressions/opinions to see whether what is under consideration is or is not under your control. Epictetus also uses the term μελέτη in the same way. Someone making progress (ὁ προκόπτων) is performing this evaluative process.
ἀταραξία, ἡ: freedom from disturbance, tranquility, which is a constituent of εὐδαιμονία.
ἀφορμή, ἡ: negative impulse; the opposite of ὁρμή; the negative impulse prevents you from doing something which will hinder you from acting appropriately, e.g., the negative impulse will keep you from becoming angry with your father or other relative.
δόγμα, τό: an opinion expressed in propositional form ( “it is good to pursue political office”); assent to this opinion will lead to action.
ἔκκλισις, ἡ: aversion, the avoidance of evil or what one supposes to be evil. ὄρεξις is its opposite.
εὐδαιμονία, ἡ: happiness, human flourishing, the goal of life. According to the Stoics, ἐυδαιμονία is “to live in harmony with nature (φύσις).”
ἐφ᾽ ἡμῖν: "in our control, up to us;" in Ench. 1 Epictetus lists four things which are under our control: ὑπόληψις (opinion), ὁρμή (impulse), ὄρεξις (desire) and ἔκκλισις (aversion). ἀφορμή (negative impulse) should be added to the list.
κακόν, τό: evil; for the Stoics, only moral vice is evil.
τὰ καθήκοντα: appropriate actions, duty; there are certain appropriate forms of behavior depending on your position or relationships in society (e.g., respect for parents and elders).
κατόρθωμα, τό: right action, virtuous action. The Stoic sage was the only one who could perform τὸ κατόρθωμα, since he would be the only one who would knowingly perform an action correctly.
μελέτη, ἡ: practice in evaluating your impressions/opinions to see whether what is under consideration is or is not under your control. Epictetus uses the term ἄσκησις in the same way. Someone making progress (ὁ προκόπτων) is performing this evaluative process.
ὄρεξις, ἡ: desire is directed toward the good or what one supposes to be good; the opposite of ἔκκλισις.
ὁρμή ἡ: (positive) impulse, which is sent out once someone assents to an impression/opinion. More specifically Epictetus maintains that impulses are directed toward τὰ καθήκοντα. ἀφορμή is its opposite.
οὐκ ἐφ᾽ ἡμῖν: “not in our control, not up to us;” in Ench. 1 Epictetus lists four things which are not under our control: σῶμα (body), κτῆσις (possessions), δόξαι (reputation), and ἀρχαί (political office).
πάθος, τό: emotion, passion, which the Stoics regarded as an excessive impulse. Compare Diss. 3.2.3: “Passion is nothing other than the failure to attain what we desire, or an encountering of what we wish to avoid” (πάθος γὰρ ἄλλως οὐ γίνεται εἰ μὴ ὀρέξεως ἀποτυχανούσης ἢ ἐκκλίσεως περιπιπτούσης). The Stoics regarded this excessive response as irrational.
προαίρεσις, ἡ: volition, will, the faculty which evaluates your impressions and makes the moral choices upon which you act.
προκόπτων, ὁ: the one who is making progress, someone who is practicing evaluating their opinions to see whether what is under consideration is or is not under their control. Compare Diss. 1.4; Ench. 12 and 48.
συγκατάθεσις, ἡ: assent given to an impression (φαντασία) or opinion (δόγμα or ὑπόληψις); it sends an impulse (ὁρμή) to act.
ὑπόληψις, ἡ: opinion; more often Epictetus uses the term δόγμα.
φαντασία, ἡ: impression, a term which covers not only our perceptions (“Here is money”), but also judgments about the perceptions (“Money is a good thing” or “One should pursue money”).
φύσις, ἡ: nature. For the Stoics, nature referred to the universe, rationally ordered and guided by the Stoic God (also called Zeus). Man’s place in the universe was to play the part of a rational moral being.