Biennial

Bi·en·ni·al

Biennial

a.
  1. Happening, or taking place, once in two years; as, a biennial election.
  2. Continuing for two years, and then perishing, as plants which form roots and leaves the first year, and produce fruit the second. (Bot.)

Biennial

n.
  1. Something which takes place or appears once in two years; esp. a biennial examination.
  2. A plant which exists or lasts for two years. (Bot.)