biennial

adjective

bi·​en·​ni·​al (ˌ)bī-ˈe-nē-əl How to pronounce biennial (audio)
1
: occurring every two years
a biennial celebration
2
: continuing or lasting for two years
specifically, of a plant : growing vegetatively during the first year and fruiting and dying during the second
Biennial herbs flower in their second year.
biennial noun
biennially adverb
What do bimonthly and biweekly mean?: Usage Guide

Many people are puzzled about bimonthly and biweekly, which are often ambiguous because they are formed from two different senses of bi-: "occurring every two" and "occurring two times." This ambiguity has been in existence for nearly a century and a half and cannot be eliminated by the dictionary. The chief difficulty is that many users of these words assume that others know exactly what they mean, and they do not bother to make their context clear. So if you need bimonthly or biweekly, you should leave some clues in your context to the sense of bi- you mean. And if you need the meaning "twice a," you can substitute semi- for bi-. Biannual and biennial are usually differentiated.

Did you know?

Biennial conventions, celebrations, competitions, and sports events come every two years. Biennials are plants that live two years, bearing flowers and fruit only in the second year. (Carrots and sugar beets are two examples; since we're only interested in their roots, we don't wait another year to see their flower and fruit.) In contrast, semiannual means "twice a year". But no one can agree whether biweekly means "twice a week" or "every two weeks", and whether bimonthly means "twice a month" or "every two months". Maybe we should stop using both of them until we can decide.

Examples of biennial in a Sentence

The governor explained the biennial budget proposal.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Hollyhock, which can be a biennial or perennial, grows its stunning flowers on rigid, towering stems. Luke Miller, Better Homes & Gardens, 27 June 2025 Fitzcarraldo Editions, Giramondo Publishing, and New Directions are teaming up to launch The Poetry in Translation Prize, a new biennial award for a poetry collection translated into English. James Folta, Literary Hub, 25 June 2025 Among the many topics related to the biennial event discussed by Donald was the case of Jon Rahm. Julio Cesar Valdera Morales, MSNBC Newsweek, 15 May 2025 Mounting tax frustrations The recall effort grew out of taxpayers’ dissatisfaction with how White and county assessment director Gail McCann Beatty set values on real estate for property tax purposes during the biennial reassessment cycle in 2023. Mike Hendricks, Kansas City Star, 24 Apr. 2025 See All Example Sentences for biennial

Word History

First Known Use

1562, in the meaning defined at sense 1

Time Traveler
The first known use of biennial was in 1562

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Cite this Entry

“Biennial.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/biennial. Accessed 6 Jul. 2025.

Kids Definition

biennial

adjective
bi·​en·​ni·​al (ˈ)bī-ˈen-ē-əl How to pronounce biennial (audio)
1
: occurring every two years
2
: growing stalks and leaves one year and flowers and fruit the next before dying
biennial noun
biennially adverb

More from Merriam-Webster on biennial

Last Updated: - Updated example sentences
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