ἕκμηνος · hekmēnos — LSJ
of six months, half-yearly, ἑκμήνους χρόνους (Pors. for ἐμμήνους) S. OT 1137; βίος Arist. HA 558a17 : Subst. ἕκμηνος, ὁ, half-year, ἐντὸς ἑκμήνου Pl. Lg. 916b; ἐν ἑγμήνῳ IG 12(9).207.52 (Eretria, iii B.C.), cf. D.C. 59.6; ἕ. (sc. ἀρχή), ἡ, Plb. 6.34.3.
six months old, of an animal, Arist. HA 562b27; μὴ πρεσβύτερον ἐνιαυσίου καὶ ἑγμήνου IG 12(5).647.8 (Ceos).