WORD OF THE DAY

Oxford and Merriam Webster define bimonthly as either twice a month or every other month. (Biweekly means either twice a week or every other week. ) The problem arises in the prefix--bi--which means both "two" and "twice."

Merriam-Webster (rather testily) explains "this ambiguity has been in existence for nearly a century and a half and cannot be eliminated by the dictionary." Harumph.

But then why do we have different words for biannual and biennial?

Which meaning do you favour? (And feel free to vent in the comments!)

EDIT to add another question: What do you mean when you hear/say "bi-weekly"?

I am beginning to find people use these terms interchangeably as (roughly) every other week. But if "biannual" is twice a year and "bimonthly" is twice a month, why isn't "bi-weekly" twice a week?