Triennium, triénnij. Ci. Three yeares spate.Iam biennium aut triennium est, quum virtuti nuntium remisisti. Ci. It is now two or three yeare since, &c.Ismariæ celebrant repetita triennia Bacchæ. Oui. The three yeares feastes, &c.Continuum triennium. Plau.
Lewis and Short: Latin dictionary
trĭennĭum, ii, n. (sc. spatium) [id.], the space of three years, three years: biennium aut triennium est, cum virtuti nuntium remisisti, Cic. Fam. 15, 16, 3; Plaut. Mil. 2, 3, 79; id. Most. 2, 2, 10; id. Stich. 1, 2, 80; 1, 3, 61; Cic. Q. Fr. 1, 1, 2, 8; Caes. B. G. 4, 4; Auct. B. Afr. 19, 3 al.