ἀνδρεία is one of the four cardinal TERMvirtues (with TERMφρόνησις, TERMσωφροσύνη, δικαιοσύνη). Literally "manliness" (from ἀνήρ, "man"), but for the Stoics it is not martial valour but knowledge.

The Stoic definition: ἐπιστήμη δεινῶν καὶ οὐ δεινῶν καὶ οὐδετέρων — "the knowledge of what is terrible, what is not terrible, and what is neither." That is, ἀνδρεία is TERMφρόνησις applied to the domain of endurance and fear (φόβος, πόνος): the correct judgment of what is truly to be dreaded (only vice) and what is not (death, pain, loss — the indifferents). Courage, then, is not the overcoming of fear by effort but the absence of fear where there is no real evil; endurance (ὑπομονή), confidence, and magnanimity are its species.

SVF III 262 ff., 264–265 (the doctrine of the four virtues and their species); DL VII 92–93 (the definitions of the cardinal virtues); Stob. Ecl. II 59–60 W; Cic. De off. I; LS 61. The Platonic background: Resp. IV 429a–430c (ἀνδρεία as the preservation of a correct opinion about what is to be feared); Lach. 194e–199e. In Marcus, in the lists of the cardinal virtues: Med. 3.6; 05-12. 11-18 stands apart: there ἀνδρεία, along with ἰσχύς and νεῦρα, is assigned to the gentle man rather than to the angry one, and gentleness is called ἀρρενικώτερον — "more masculine" than rage.