I am an advocate for ‘plain English’. Writing that doesn't let cleverness get in the way of communication. Possibly informed by the international nature of my career and the vast amount of jargon and double speak that I have to deal with. While I love the rich tapestry of the English language, the vagaries, wild proliferations and curious expansions can be challenging to defend.
Motivated by curiosity and a need to resolve this issue definitively after two factions presented themselves in a team meeting, I did some research to settle the debate. If you look up the adjective bi-weekly in Merriam Webster, it states ‘occurring every two weeks’ AND ‘occurring twice a week’. Bi-monthly is defined as ‘occurring every two months’ AND ‘occurring twice a month’.
The definition is the same regardless of your lexicographer. The Oxford English Dictionary reflects the same conundrum as the Cambridge Dictionary.
What’s the solution? Well, there isn’t one as it’s an intractable problem.
I’ve resolved to remove the ambiguity and use ‘every two weeks’ or ‘every other month’ as cumbersome and inelegant as that is. Although technically, both could be declared polysemous which is a great word in itself.
Merriam Webster produce Word at Play where they explore words in use or ‘usage notes’. They’re an interesting and fun look at language and they featured this problem in ‘The Ambiguity of Biweekly and Bimonthly’.