[ bahy-an-yoo-uhl ]
/ baɪˈæn yu əl /
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occurring twice a year; semiannual.
occurring every two years; biennial.
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Origin of biannual

First recorded in 1875–80; bi-1 + annual

words often confused with biannual

See bi-1.


bi·an·nu·al·ly, adverb


biannual , biennial, semiannual, semiyearly (see confusables note at bi-1)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021


What does biannual mean?

Biannual can mean two things: occurring once every two years or occurring twice per year.

Biannual is a synonym of biyearly, which can also be used to mean every two years or twice per year. (Biyearly can also mean “lasting for two years,” but this meaning is rarely used.)

The adverb form of biannual is biannually.


  • The Olympic Games are biannual, meaning they happen every two years.
  • This is a biannual meeting—we have it in April and October.

Where does biannual come from?

The first records of biannual come from the 1870s. Bi- is a prefix meaning “twice” or “two,” and annual means “happening every year” or “once a year.”

People are often confused about whether to use biannual or biyearly and for good reason: both can mean “twice per year” or “every other year.” The thing to remember is that one isn’t more “correct” than the other. However, biannual is more commonly used than biyearly.

There are several other similar time-related terms that can make things even more confusing. Semiannual and semiyearly both mean occurring twice a year or lasting for half a year. Another word, biennial, means happening every two years or lasting for two years, but this is used less commonly than biannual or biyearly.

Yes, you can sometimes figure out what biannual means through the context of the sentence. But not always. When a coworker tells you a meeting is biannual, it probably means it happens twice a year, but it could also mean it happens every two years. (Hopefully it doesn’t mean that it lasts for two years.)

Here’s the best (and maybe only) way to be perfectly clear: just say “twice a year” or “once every two years.”

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What are some other forms related to biannual?

What are some synonyms for biannual?

What are some words that share a root or word element with biannual

What are some words that often get used in discussing biannual?

What are some words biannual may be commonly confused with?

How is biannual used in real life?

Biannual is perhaps most commonly used to describe events that occur every two years, such as the Olympics, but this isn’t always the case, so it’s always best to make sure.



Try using biannual!

To avoid confusion, what’s the best way to say twice a year

A. biyearly
B. biannual
C. biennial
D. twice a year

How to use biannual in a sentence

British Dictionary definitions for biannual

/ (baɪˈænjʊəl) /

occurring twice a yearCompare biennial

Derived forms of biannual

biannually, adverb
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012