I agree that it has always been understood to mean 'every two weeks' especially when referring to pay cycles or magazine subscriptions, but most dictionaries now list two definitions: every two weeks or twice a week (semiweekly) with 'every two weeks' being the most common usage.

Tracy

>Semi-annual means twice a year, so semi-weekly means twice a week. Bi-weekly means every two weeks. However, many people don't know the difference and will use bi-weekly to mean twice a week.
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>>Can anyone please give a clue: does bi-weekly mean twice a week or twice a month?