Trī-ēn'ni-al, a.

a. [Lat. triennium (sc. spatium), the space of three years, from tri, q. v., and annus, year; Fr. triennal, Sp. trienal, trienal, It. triennale.]

1. Continuing three years; as, triennial parliaments.
2. Happening, coming about, or appearing once in every three years; as, triennial elections; a triennial catalogue.