bi·​an·​nu·​al (ˌ)bī-ˈan-yə(-wə)l How to pronounce biannual (audio)
: occurring twice a year
biannually 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?

When we describe something as biannual, we can mean either that it occurs twice a year or that it occurs once every two years. So how does someone know which particular meaning we have in mind? Well, unless we provide them with a contextual clue, they don't. Some people prefer to use semiannual to refer to something that occurs twice a year, reserving biannual for things that occur once every two years. This practice is hardly universal among English speakers, however, and biannual remains a potentially ambiguous word. Fortunately, English also provides us with biennial, a word that specifically refers to something that occurs every two years or that lasts or continues for two years.

Examples of biannual in a Sentence

Politicians still tremble when Barry begins his biannual comeback flirtations.  … But if they'd spent less time looking over their shoulders and more time looking over election returns, they'd have seen that Barry was likely heading for a poleaxing when he called it quits. Michael Schaffer, New Republic, 22 Apr. 2002
… have recommended routine annual or biannual mammographic screening for asymptomatic women without a personal or family history of breast cancer, starting at the age of 40. Nels Marcus Thygeson, Journal of the American Medical Association, 8 July 1986
One of the more fascinating commonplace facts about the whitetail is its biannual change of color. Summer, when deer come "into the red," as the saying goes, scant reddish-brown hairs replace the winter coat. Fall, deer come back "into the blue," though less than blue, with a thick pelage of hollow, grayish-tan hairs … John G. Mitchell, Smithsonian, November 1982
The group holds biannual meetings in December and July. The art show is a biannual event that won't happen again for two more years.
Recent Examples on the Web Being a Southern Beach Lover means taking annual—if not biannual—trips to fuel our obsession. Tara Massouleh McCay, Southern Living, 18 Mar. 2024 Does the time change affect health? Americans experience physical health problems caused by the biannual time changes, according to a study by the National Institutes of Health. Amy Huschka, Detroit Free Press, 9 Mar. 2024 The mile run was part of the Presidential Physical Fitness Test, a biannual assessment given to elementary through high school students. Danielle Friedman, New York Times, 5 Mar. 2024 For more immediate tactical considerations and midterm strategic alignment, quarterly or biannual reviews are highly effective. Benjamin Laker, Forbes, 15 Feb. 2024 The Academy’s other programs include its biannual daylong Next Level Summit and the Original Voices fellowship and accelerator for documentary filmmakers. Rebecca Sun, The Hollywood Reporter, 15 Feb. 2024 Tesla apparently sent out the single-line query for each job after canceling some employees’ biannual performance reviews, the people told the outlet. Andy Kalmowitz / Jalopnik, Quartz, 8 Feb. 2024 The country music superstars announced their acquisition of Field & Stream magazine on Thursday, sharing plans to relaunch the outdoor brand as a biannual print magazine, refreshed digital platform, clothing company and — fitting for the artist duo — a music festival. Malia Mendez, Los Angeles Times, 26 Jan. 2024 The biannual temporal event allows for more daylight at night between mid-March to early November. Skyler Caruso, Peoplemag, 9 Mar. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'biannual.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1877, in the meaning defined at sense 1

Time Traveler
The first known use of biannual was in 1877


Dictionary Entries Near biannual

Cite this Entry

“Biannual.” Dictionary, Merriam-Webster, Accessed 19 Apr. 2024.

Kids Definition


bi·​an·​nu·​al (ˈ)bī-ˈan-yə(-wə)l How to pronounce biannual (audio)
: occurring twice a year

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