Let's (try to) end the debate: Does biweekly mean twice a week or twice a month?

A dictionary search for biweekly likely won't clear up confusion about how often a biweekly meeting is being held. 

Merriam-Webster, Dictionary.com, and the Cambridge Dictionary each offer two different definitions for the adjective: occurring twice a week or occurring every two weeks. The language conundrum goes beyond biweekly; bimonthly and biannual also have competing definitions. Is the bimonthly meeting twice a month or is it every two months? Is the biannual family reunion twice a year or once every two years? 

The different definitions have left people — even the ones working at dictionaries — scratching their heads for a long time. 

"This is absolutely a problem of English, just generally, we just don't have a good tool for this," Merriam-Webster editor Peter Sokolowski said. "It is odd that bi, which means two and twice, then becomes confused with itself. It's an unusual circumstance linguistically."

People search biweekly, bimonthly and biannual on the Merriam-Webster website often, Sokolowski said.

"A lot of the tension that we get is for new words or slang words or things, but actually, it's this kind of word that is the bread and butter of the dictionary," Sokolowski said. "You know, these ambiguities of English that send people to the dictionary day in and day out, year in and year out."

The Associated Press, which guides the style choices of many news organizations, took a stand on the definition it uses. It says biweekly means every other week and that semiweekly means twice a week.

In day-to-day life, Sokolowski advises ensuring you provide context if you plan to say biweekly, bimonthly or biannually. Or just work around it — say twice a week, twice a month and so on. Laurel MacKenzie, associate professor with the NYU Department of Linguistics, agreed.

"Sometimes you really just have to paraphrase because it can be totally ambiguous without context," she said.

Michael Adams, an Indiana University English professor, said bringing back the word fortnight, a period of 14 days, and the word fortnightly, something occurring once every 14 days, would solve a lot of the problems with biweekly. 

"So if we're looking for a solution to the problem, let's bring fortnight and fortnightly back into use," Adams said. "And then we don't have to worry about biweekly or bimonthly meaning two things, or about inserting semiweekly or semimonthly which users clearly, from the historical record, do not prefer."

A review of the Corpus of Historical American English, which can be used to determine how frequently a word is used compared to other words, shows fortnight and fortnightly have been used more frequently than biweekly and that biweekly, in turn, has been used more often than semiweekly, Adams said. 

"That's the result of fortnight being an old English word so well established historically that people saw no reason to use biweekly to mean every two weeks," Adams said.

While fortnight and fortnightly were much more frequently used historically than biweekly, their usage began to peter out a little bit after the 1950s, Adams said. 

And though the ambiguous definition of biweekly has been confusing people for a long time, dictionaries haven't decided to stick to just a single definition. 

"The basic issue is that language isn't math," Sokolowski said. 

Instituting a language change and getting people to follow along with it is challenging, MacKenzie said. When language does change, it's usually to be more equitable in how terms are phrased. 

"It's very hard for anybody to litigate or legislate language," she said.