Moira is one of the oldest words in Greek ethics. Literally: "a part, a share, a stretch," from the verb μείρομαι ("to receive as one's lot, to have as one's portion"). In Homer and the tragedians it is what is measured out to a person: death, fortune, lineage, event; moira is personified as a goddess (or three goddesses — the Moirai, Κλωθώ, Λάχεσις, Ἄτροπος — who spin, measure, and cut the thread of life). The Stoics reinterpret the notion: μοῖρα is not a blind irrational power but functionally the same reality as TERMεἱμαρμένη, πρόνοια, the Logos, and TERMthe nature of the whole — viewed under the aspect of "the marking-off," "the measuring-out" of each part.

Hom. Il. 16.434 (μοῖρα as the lot of death); Hes. Theog. 904–906 (the three Moirai); Plat. Resp. 617c (the myth of Er — the Moirai and the spindle of Ananke). In the Stoics: SVF II 913–917 (the doctrine of fate, using both terms); Stob. Ecl. I 79 W. The simple word μοῖρα is rare in Marcus (he prefers derivatives: συμμεμοιραμένα, εὐμοιρία); the important places are Med. 4.34 and 5.8.

Relation to TERMheimarmene: both words come from the same root, μερ-/μοιρ-. Μοῖρα is a nominal concept ("share"); εἱμαρμένη is a verbal form (a perfect-passive participial substantive of μείρομαι, "the measured-out"). They are not strict synonyms: μοῖρα is what has been measured out; εἱμαρμένη is the property that everything in the cosmos has been measured out and is coherent. In Marcus this pair generates a lexical cluster that runs through Book II:

• 02-02 — μηκέτι τὸ TERMεἱμαρμένον δυσχερᾶναι: the general posture of accepting what has been measured out;
• 02-05 — δυσαρεστήσεως πρὸς τὰ συμμεμοιραμένα: what is "measured out together with me" (a derivative of συν + μείρομαι);
• 02-06 — ἐν ταῖς ἄλλων ψυχαῖς τιθεμένῃ τὴν σὴν εὐμοιρίαν: "a good moira" as a synonym of TERMεὐδαιμονία.

Thematically: μοῖρα is the aspect of TERMheimarmene on the side of "the particular," at the moment when "my share" is locally singled out from the whole of what has been measured out. It therefore works well in ethical contexts (acceptance of one's lot, the distinction between my share and another's), where TERMheimarmene tends to operate in cosmological ones.