My point is that if you think the rules we learn in school about language are the same rules that allow us to communicate and understand each other, you're failing to realize the massive complexity of language.
As for those "bi-" words, there seems to be more consistency with "biannually", than with "biweekly", or "bimonthly". Oxford only gives a single definition for "biannual":
As for those "bi-" words, there seems to be more consistency with "biannually", than with "biweekly", or "bimonthly". Oxford only gives a single definition for "biannual":
http://www.oxforddictionaries.com/definition/english/biannua...
As a professional linguist, there are millions of questions about language I find more exciting than this :)