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

Between 2023 and 2024, the property’s tax bill jumped from around $75,000 to more than $100,000, following the county’s triennial reassessment. — Evgenia Anastasakos, Chicago Tribune, 6 Sep. 2026

The Fellowship program recognizes fifteen disciplines, focusing on five each year on a triennial basis. — News Desk, Artforum, 24 July 2026

This selection highlights 30-plus portraits from more than 3,300 entries to the triennial Outwin Boochever Portrait Competition. — Washington Post Staff, Washington Post, 15 May 2026

While the triennial tournament was underway, however, some new faces and non-roster invitees had a chance to shine in Red Sox camp. — Gabrielle Starr, Boston Herald, 21 Mar. 2026

Word History

First Known Use

1562, in the meaning defined at sense 1

Rhymes for triennial

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