Biennial means happening once every two years. In biology, it can also describe plants that live for two years and usually flower in the second year.
From Latin “bi-” meaning “two” and “annus” meaning “year.” The “-ial” ending makes it an adjective about time.
People constantly mix up “biannual” (twice a year) and “biennial” (every two years), so writers sometimes avoid both and say “twice a year” or “every two years” instead. When you see “biennial,” think of a two-year cycle, not two events in one year.
Complete word intelligence in one call. Free tier — 50 lookups/day.