I.a period or space of two years, two years: jam biennium est, cum, etc., Plaut. Merc. 3, 1, 35: “intra tempus biennii,” Col. 3, 9, 6: “hoc factum est ferme abhinc biennium,” Plaut. Bacch. 3, 2, 4 (imitated by Ps.-Plaut. Merc. prol. 12): “biennium ibi perpetuum misera illum tuli,” Ter. Hec. 1, 2, 12; Caes. B. G. 1, 3; Cic. Phil. 5, 3, 7; Liv. 5, 14, 2: “biennium provinciam obtinuit,” Cic. Verr. 2, 3, 93, § 216; 2, 4, 30, § 67: “lex usum et auctoritatem fundi jubet esse biennium,” id. Caecin. 19, 54; Quint. Ep. ad Tryph. 1; id. Inst. 1, 12, 9: “biennio postquam abii,” Plaut. Bacch. 2, 1, 1: “comitia biennio habita,” Liv. 5, 14, 2: “matres, quae biennio durant,” Plin. 11, 21, 24, § 73; Suet. Galb. 7: “consulatum biennio post ultro petiit,” id. Aug. 26: “intra tempus bienni,” Col. R. R. 3, 9, 6: “intra biennium,” Quint. 1, 2, 9: “ultra biennium,” Tac. A. 1, 1.
bĭennĭum , ii, n. bis-annus,