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Occuring every two days, just as biennial means occuring twice per year.

Similar to biennial whose latin bi- prefix bi- means "two," so bidiem means "every two days."

See also bidaily. The bi- prefix on bidaily means "divides into two," so that bidaily events occur twice each day.
I need you to report bidiem, every other day.
by Brian Layman January 11, 2008