Biannual vs Biennial: Which Should You Use?

English words can be confusing for many reasons, but most of the frustration probably stems from words with similar or near-similar spellings, yet different meanings or pronunciations.

The words “biannual” and “biennial” are two such terms that are frequently used interchangeably, but are actually quite different. Let’s take a closer look at why people keep getting confused between these two.

What Does Biannual Mean?

Biannual is an adjective that means occurring twice in a year. It’s composed of the prefix “bi-,” meaning two, and the Old French word “annual,” meaning “appointed by the year” or “occurring once a year.”

Examples:

1. A solstice happens biannually, once in the summer and another in the winter.
2. They live in New Jersey, but visit New York biannually.
3. She works from home but needs to attend biannual meetings at the office.

What Does Biennial Mean?

Biennial is also an adjective, but means occurring only once every two years. It comes from the Latin word biennium, which means a two-year period.

Examples:

1. We used to visit our grandparents biennially, but now we do it every year instead.
2. A biennial plant blooms in its second year and then dies.
3. The World Taekwondo Championships is a biennial event.

How to Avoid Confusion

Many people mistakenly use biannual and biennial interchangeably because both words look and sound the same. However, there are tricks for reminding yourself which is which.

Use the a in biannual to help you remember that the word is used for things that happen twice a year.

Use the e in biennial to help you remember that it means things that happen only once every two years.

Or, you can also base it on how many months they both occur. Biannual events happen every 6 months, while biennial events happen every 24 months.

Other Bi- Words

Aside from biannual and biennial, there are other bi- words that often trip people up. The most common of these are biweekly, bimonthly, and biyearly.

The problem lies with the prefix bi- itself. It means both “coming or occurring two times” and “coming or occurring every two,” makes the meaning of bi- words ambiguous.

Perhaps the best way to avoid confusion is to side-step these words completely.

Use a different prefix like semi-, which clearly means half of something. Semiannual, semimonthly, and semiweekly are far less confusing.

Or, if brevity isn’t an issue, use words that clearly explain what you mean. Use “every two months,” “once every two years,” and any similar phrases.

If you still prefer to use bi-words, make sure that you provide sufficient context to explain which of its two meanings you’re employing.

What other similar-sounding words frustrate you? Share them in the comments below!

 

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