CULTURE WATCH : One Prefix Equals Twice the Chaos

B iannual means every two years, bimonthly means every two months, and biweekly means every two weeks. Right? Ah, if only it were true.

In fact, biannually, bimonthly and biweekly are used by some people to mean the same thing as semi-annually, semi-monthly and semi-weekly, that is, twice a year, twice a month and twice a week, respectively.

While the publishing world, for instance, generally uses bimonthly to mean every two months, the academic world often uses the same word to mean twice a month, as in bimonthly examinations.

Needless to say, this ambiguity can cause serious confusion and panic.

It’s the Latin prefix bi that causes problems. Bi, of course, can mean two, as in binary, biathlon and bicycle. But it can also mean into two, as in bisect and bifurcate.

So, during the course of our language’s history, biannual, bimonthly and biweekly acquired double meanings, leading to our present-day dilemma.

As for biannual et al.: Always use biannual, bimonthly and biweekly to mean every two years, every two months or every two weeks. But make it clear, even at the risk of being redundant, that you mean two, not twice, e.g.: “our bimonthly magazine, published six times a year.”