/ Dictionary / Index B bimillennium: Meaning and Definition of Find definitions for: bi•mil•len•ni•um Pronunciation: (bī"mi-len'ē-um), [key] — pl. -len•ni•ums, -len•ni•a a period of two thousand years. a two thousandth anniversary. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: bimillennium (Thesaurus) bimillenary Bimini Islands Related Content Daily Word Quiz: acquiesce Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language