triennial
Americanadjective
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occurring every three years.
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lasting three years.
noun
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a third anniversary.
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something that appears or occurs every three years.
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a period of three years; triennium.
adjective
noun
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a third anniversary
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a triennial period, thing, or occurrence
Other Word Forms
Etymology
Origin of triennial
First recorded in 1555–65; trienni(um) + -al 1
Explanation
Use triennial to describe anything that happens every three years. Your family just held its triennial reunion, so you're going to have to wait three years to see those distant cousins again. Meetings, conferences, and art shows are some of the many things that might occur every three years, or on a triennial basis. In Judaism, the triennial cycle is an ancient practice of reading the entire Torah over the course of a three-year period. Triennial can also mean "lasting for three years," like a sports player's triennial, or three-year, contract. The word derives from Latin roots meaning "three" and "yearly."
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Global foreign exchange turnover in over the counter markets averaged $9.5 trillion per day in April, up 27% from 2022, according to revised data for this year’s BIS triennial forex survey.
From The Wall Street Journal ● Dec. 8, 2025
Still, complications loom — starting with the triennial World Baseball Classic scheduled for next March.
From Los Angeles Times ● Nov. 17, 2025
Ironically, the United States is scheduled to present its triennial compliance report on Convention 182 this year.
From Washington Post ● Apr. 28, 2023
However at their triennial assembly in Montreal this week they finally agreed to support a net zero target for 2050, despite grumbles from China and Russia.
From BBC ● Oct. 7, 2022
It was an invitation to the Solvay Conference, an elite triennial international convocation in Brussels, Belgium.
From "Big Science" by Michael Hiltzik
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
