I was taught that biweekly and bimonthly meant twice a week and twice a month, respectively. I can even reference this in my very old dictiionaries as being correct. I now see definitions in dictionaries that define biweekly as twice a week AND every other week (Random House, Webster’s), and bimonthly as every other month. These “new” definitions are also used in every-day conversation, and can be confusing (I now have reverted to twice a week or every other week to clarify). When did this change? If biannually is always twice a year, why are not bimonthly and biweekly twice a month and twice a week?