Henry George Liddell, Robert Scott, A Greek-English Lexicon

A.the number thirty, “ἐς τριακάδας δέκα ναῶν” A.Pers.339.

II. the thirtieth day of the month. Hes.Op.766, IG12.845.2, 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” SIG286.13 (Milet., iv B. C.); of a festival in the cult of Zeus Panamaros, ib.900.36 (iv A. D.).

2. a month, containing 30 days, Luc.Luct.16, Rh.Pr.9.

III. at Athens, a religious association of thirty persons, fraction of the deme, IG22.1214.18, cf. Poll.8.111.

2. 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.