triennial
UK /tɹaɪˈɛniəl/ US /tɹaɪˈɛniəl/
adj 2noun 2
Definitions
adj
1
Happening every three years.
triennial elections
They were constantly summoned to a triennial festival : and the most approved songs delivered at this assembly were ordered to be preserved in the custody of the king's historian or antiquary
2
Lasting for three years.
triennial parliaments; a triennial reign
September 13 1621, James Howell. letter to Sir William Saint John Triennial Subsidies
noun
1
A third anniversary.
2
A plant that requires three years to complete its life-cycle.
Your note
not saved0 chars