What do lengths of time with the "bi" prefix mean"? I have understood bicentennial as once every two hundred years, but biannual as meaning twice a year. Do biweekly and bimonthly mean twice a week or month, or once every two weeks or months?
If this prefix is not used consistently, is there any rationale as to why it isn't?
Best Answer
Bi- usually means "every two" (as in "every two [weeks/months/years, etc.]." But it can also mean "twice every [week/month/year, etc.]." To avoid confusion, I save bi- for "every two" and use semi- to mean "twice every." I wish everyone did.