triennial

adjective

tri·​en·​ni·​al (ˌ)trī-ˈe-nē-əl 

1

: occurring or being done every three years

the triennial convention

2

: consisting of or lasting for three years

a triennial contract

triennial noun

triennially

(ˌ)trī-ˈe-nē-ə-lē 

adverb

Examples of triennial in a Sentence

Recent Examples on the Web

The Minnesota Department of Health on Tuesday released the results of the triennial survey of the state’s fifth, eighth, ninth and 11th grade students. —Dené K. Dryden, Twin Cities, 10 Dec. 2025

Thanks to the new rule instituted by the Hall this year, Clemens only has one more chance on this triennial ballot. —Gabrielle Starr, Boston Herald, 7 Dec. 2025

Representatives of the European Space Agency's (ESA) 23 member states are set to meet at the end of November in Bremen, Germany, to decide the agency's direction for the next three years and agree on its next triennial budget. —Tereza Pultarova, Space.com, 18 Nov. 2025

Wolff analyzed data from the Federal Reserve’s triennial Survey of Consumer Finances. —Greg Iacurci, CNBC, 12 Nov. 2025

Word History

First Known Use

1562, in the meaning defined at sense 1

Rhymes for triennial

• biennial
• centennial
• decennial
• millennial
• perennial
• quadrennial
• quinquennial
• bicentennial
• sesquicentennial

Kids Definition

triennial

adjective

tri·​en·​ni·​al (ˈ)trī-ˈen-ē-əl 

1

: consisting of or lasting for three years

2

: occurring or being done every three years

triennial noun

triennially

-ē-ə-lē 

adverb