Biweekly, the reader wrote, means something happens twice a week. Biweekly, the Associated Press Stylebook and other sources say, means something happens every other week. Biweekly, the Webster’s New World Dictionary (Fourth Edition) says, means “1) once every two weeks, 2) [Now rare] twice a week.” Two other dictionaries, Random House’s Webster’s College and Merriam-Webster’s Collegiate, give the definitions for biweekly as “once every two weeks” first and “twice a week” second. Those who hold that biweekly means every other week prefer semiweekly as the word for twice a week. Bimonthly and semimonthly have a similar distinction.
But then biannual and biennial come along. Biannual, my stylebook and dictionary say, means twice a year, and is a synonym for semiannual. The word for something that happens every other year is biennial, which also describes something that lasts two years.
The best advice about these bi- words comes from the very sensible Bill Bryson, who writes in “Bryson’s Dictionary of Troublesome Words,” that the bi- words are so ambiguous that writers are better off using “every two months [or weeks]” or “twice a month [or week].” The first rule of writing is clarity, and if you are confused by the bi- words, your readers might be, too. Spell it out for them.
This article was originally posted by the Raleigh News & Observer, a subsidiary of The McClatchy Co.; is posted here to provide continuity; and is copyright © 2011 The News & Observer Publishing Company, which reserves the right to remove this post.