Lewis & Short

trĭmestris, e, adj. [ter-mensis], of three months.

  1. I. Adj.: haedi, three months old, Varr. R. R. 2, 3, 8: spatium, Plin. 37, 10, 59, § 163: anni Arcadum, id. 7, 48, 49, § 155: consul, Suet. Caes. 80: satio, i. e. that ripens in three months, Col. 2, 4, 9: semen, id. 2, 9, 7; so, triticum, Plin. 18, 7, 12, § 69: aves, i. e. that remain with us but three months, id. 10, 25, 36, § 73: annorum caelique vices, Aus. Edyll. 11, 24.
  2. II. Subst.: trĭme-strĭa, ĭum, n., seeds that ripen three months after sowing, Col. 2, 12, 9; 11, 2, 20; Plin. 18, 26, 65, § 240.