Commonly Confused Words: Biannual vs. Biennial

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This week’s pair of words often cause confusion in the world of business. Read on to find out what each word means and to learn tricks to help you tell them apart. 

What does each word mean?

The adjective biannual describes something that occurs or is payable twice each year. 

Click here for the full Spellzone dictionary definition of the word.

Here is biannual used in some example sentences:

  • The theatre company performs a biannual show in the community garden which is free for members of the public to attend. 
  • The payment will be due biannually at the discussed rate. 
  • The senior staff members met biannually to discuss progress and make plans for the future. 

If something is biennial, it occurs every other year. The adjective is also used to describe plants that have a life cycle which spans two seasons. 

Click here for the full Spellzone dictionary definition of the word.

Here is biennial used in an example sentence:

  • The biennial art exhibition is hosted by a different city each time. 
  • Since moving to Australia, he was only able to visit his family and friends biennially and missed them very much.
  • The biennial championships will be taking place this summer. 
  • A variety of plants – from carrots to forget-me-nots – are biennial species. 

Where does each word come from? 

Biannual dates to 1837 and derives from the Latin bi- meaning ‘two’ and the Old French annual meaning ‘appointed by the year’ or ‘occurring once a year’. Annual comes from the Medieval Latin annualis meaning ‘yearly’, which corresponds to the Latin annalis (the adjective form of annus meaning ‘year’).  

Biennial dates back to the 1620s when it meant ‘lasting for two years’. From 1750, it started being used to mean ‘occurring every two years’. The word comes from the Latin biennium meaning ‘two-year period’, which – like biannual – comes from bi- and annus.

Are there any tricks to help remember the difference between biannual and biennial?

  • Use the a in biannual to help you remember that the word describes two events that always happen in the same year.
  • Use the e in biennial to help you remember that the word describes something that happens every two years/every other year. 

Where can I find other posts about easy-to-confuse words?

You may also be interested in: 

Sources: The Online Etymology Dictionary.


13 May 2019
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