τριακοστός

ή, όν
A. thirtieth, Pi. O. 8.66, IG 12.304.29, Hdt. 4.44,5.89, Hp. Aph. 4.36, X. Cyr. 5.3.6, PCair.Zen. 236.6 (iii B. C.), etc.; Aeol. τριάκοιστος [α] IG 11(4).1064b23 (Delos).
II. ἡ τ. duty of one-thirtieth, D. 20.32.
Liddell, Scott & Jones
A Greek-English Lexicon, 1940
An open-access project