τρῐᾱκάς · triakas — LSJ
the number thirty, ἐς τριακάδας δέκα ναῶν A. Pers. 339.
the thirtieth day of the month. Hes. Op. 766, IG 1(2).845.2, 7.2712.69 (Acraeph.), PCair.Zen. 150.8 (iii B. C.), Dsc. Eup. 1.146, Hippiatr. 97; τ. ἡ πικρή (when school fees were due) Herod. 3.9; first used by Thales, acc. to D.L. 1.24. At Athens the τριακάδες were dedicated to the memory of the dead, Harp., Poll. 1.66, etc.; offerings were made to Hecate, Ath. 7.325a, etc.; ἡ τῶν τ. ἀνιέρωσις Tab.Defix. 99.12; ἐπαρᾶσθαι ταῖς τριακάσιν SIG 286.13 (Milet., iv B. C.); of a festival in the cult of Z
a month, containing 30 days, Luc. Luct. 16, Rh.Pr. 9.
at Athens, a religious association of thirty persons, fraction of the deme, IG 2(2).1214.18, cf. Poll. 8.111.
at Sparta, either = 30 families (1/10 of an oba), or = 10 families (1/30 of an oba), or simply a company of thirty, Hdt. 1.65.