[ad. Gr. τριᾱκοντάς, αδ-, f. τριάκοντα thirty.] The number thirty, or a set of thirty. So Triacontaëterid [ad. Gr. τριακονταετηρίς, -ιδ, f. τριακονταετής adj. of or for thirty years], a period of thirty years, or a festival recurring every thirty years; Triacontahedral a. [Gr. ἔδρα base, side], contained by thirty faces, esp. by thirty rhombs, as a crystal; Triacontarchy Anc. Gr. Hist. [ad. Gr. τριακονταρχία, f. ἀρχή rule], the rule of the Thirty at Athens (see THIRTY A. 1 c); Triaconter [ad. Gr. τριακοντήρης], an ancient Greek galley with thirty oars.
1621. Bp. Mountagu, Diatribæ, 258. Their Ogdoades, Duodecads, *Triacontads,… and all the Æones, blasphemous speculations.
1839. Fraser’s Mag., XX. 202. The *Triacontaëterid of the pillar of Rosetta—the grand period of the Panegyres, or festivals of the gods, which returned each thirty years. Ibid., 328. The great triacontaëterid or panegyry of the resurrection.
1805–17. R. Jameson, Char. Min. (ed. 3), 201. A Crystal is said to be … *Triacontahedral when its surface consists of thirty rhombs.
1852. Grote, Greece, II. lxxii. IX. 259. Isokrates, who speaks with indignant horror of these Dekarchies,… denounces those features which they had in common with the *Triakontarchy at Athens.
1859. Rawlinson, Herodotus, IV. cxlviii. III. 124. Theras … took ship, and sailed, with three *triaconters, to join the descendants of Membliarus. Note, Triaconters were vessels of 30 oars, 15 on each side.
