Lewis Short
(adjective) : trīgārĭus, a, um, triga
* Of or belonging to a triga; used only as subst.
* Trīgārĭus, ii, m., one who drives a threehorse chariot, Plin. 28, 17, 72, § 238; 29, 1, 5, § 9.
* Trīgārĭum, ii, n.
* A place in which trigae (and horses in general) are trained and exercised, Plin. 37, 13, 77, § 202; cf.: trigarium τόπος, ὅπου ἵπποι γυμνάζονται, Gloss. Philox.
* As a nom. propr., a place or square in Rome in the ninth region, Inscr. Orell. 4266.
* (Acc. to triga, II.) The number three, Mart. Cap. 7, § 733; 9, § 895.
Charlton T. Lewis, Charles Short, A Latin Dictionary