n.
Pronunciation: ( ˌ )tr ī - ' e-n ē - ə l
Function: adjective
Date: 1562
1 : occurring or being done every three years <the triennial convention>
2 : consisting of or lasting for three years <a triennial contract>
– triennial noun
– tri · en · ni · al · ly \ -n ē - ə -l ē \ adverb