Lexical Definition

‎τριάκοντα‎ triákonta (tree-ak'-on-tah) thirty ^G:A-NUI
the decade of ‎τρεῖς‎

thirty.

Abbott-Smith

τριάκοντα, ἱο, αἱ, τά indecl. (< τρεῖς),
thirty: Mt 13:8, al.

Abbott-Smith References

Liddell-Scott-Jones

τριάκοντα [ᾱκ],

Epic dialect and Ionic dialect τρῐήκ-, late Gr. τρῐάντα (which see), οἱ, αἱ, τά, indeclinable; but genitive τριηκόντων [Refs 8th c.BC+] also in later Epic dialect, [Refs 3rd c.BC+]:—thirty, [Refs 8th c.BC+]; τ. καὶ ἕνα thirty-one, [Refs 3rd c.BC+]

__II οἱ τ., especially,
__II.1 at Sparta, a council of war of thirty, [Refs 5th c.BC+]
__II.2 at Athens, the Thirty, commonly called the thirty tyrants, appointed on the taking of Athens [Refs 5th c.BC+]
__II.3 certain magistrates, see at {τεσσαράκοντ; οἱ λογισταὶ οἱ τ}. [Refs]. [In late epigram ᾰκ, [Refs]