Bi*en"ni*al (&?;), a. [L. biennalis and biennis, fr. biennium a space of two years; bis twice + annus year. Cf. Annual.] 1. Happening, or taking place, once in two years; as, a biennial election.
2. (Bot.) Continuing for two years, and then perishing, as plants which form roots and leaves the first year, and produce fruit the second.
Bi*en"ni*al, n. 1. Something which takes place or appears once in two years; esp. a biennial examination.