Lewis & Short

trīni (terni), ae, a, num. distr. adj. [tres], three each, three.

  1. I. Lit.: ipse cum tribus legionibus circum Samorabrivam trinis hibernis hiemare constituit, Caes. B. G. 5, 53: trina sacrificia in die, Suet. Ner. 56: castra, Caes. B. G. 7, 46; Liv. 9, 43, 6: litterae, Cic. Att. 11, 17, 1; cf. Varr. L. L. 10, § 67 Müll.
  2. II. Transf., threefold, triple, = triplex: trinis catenis vinctus, Caes. B. G. 1, 53: subsidia, Auct. B. Alex. 37, 3: soles, Plin. 2, 31, 31, § 99: lunae, id. ib.: nomina, Ov. F. 6, 216: trina bella civilia, plura externa, Tac. H. 1, 2: miles Vitellianus trinis et ipse praesidiis occurrit, id. ib. 3, 82: capita (Cerberi), Sen. Herc. Fur. 783.
    1. B. Sing.: trīnus, a, um, adj., three, triple, three each: cantus trino conficitur versu, Plin. 10, 35, 52, § 106: trino relicto praesidio, Auct. B. Afr. 80, 2: forum, Stat. S. 4, 9, 15: genus interdictorum, Aus. Idyll. 11, 63; 11, 66.
      1. 2. Mostly in phrase, trinum nundinum, the time of three nundinae or market-days; v. nundinus, III.
        By the lex Caecilia et Didia, B. C. 98, that a promulgatio trinum nundinum, or a putting up in public for at least seventeen days, should be made of any proposed law before taking a vote on it, Cic. Dom. 16, 41; id. Phil. 5, 3, 8.