trĭārĭi, ōrum, m. [tres],
a class of Roman soldiers who formed the third rank from the front , the triarii , Varr. L. L. 5, § 89 Müll.: etiamsi te sors inter triarios posuerit, Sen. Tranq. 3, 10; Liv. 22, 5, 7: a primā acie ad triarios sensim referrebantur, id. 8, 8, 11; 8, 10, 6; cf. Becker, Antiq. 3, pt. 2, p. 249 sq.