adjective
- pertaining to or in honor of a 200th anniversary: bicentennial celebration; a bicentennial exposition.
- consisting of or lasting 200 years: a bicentennial period.
- occurring every 200 years: the bicentennial return of a comet.
noun
- a 200th anniversary: The United States had its bicentennial in 1976.
- a celebration of such an anniversary.
also bi-centennial, 1843 (adj.), 1871 (noun), American English, from bi- + centennial (q.v.). In rivalry with bicentenary (1831) which seems to have been the more common word in Britain.