Biannual means happening twice in a year. A biannual review, biannual meetings, held biannually.
It is a genuinely dangerous word, because biennial means every two years and the two are constantly confused — careful writers avoid both and say twice a year or every two years. Semiannual is unambiguous and mostly American.
1adjectivebiannualHappening twice in a year.
“The club holds its biannual meeting every January and July.”
biannual is a frequency.
Latin
annuālem
English
annual
English, today
biannual
Built from
From bi- + annual. annual First attested around 1382, borrowed from Latin annuālem, annuālis, related to Latin annālis, adjective form of annus (“year”). Used to categorize plants since 1710.
Etymology from Wiktionary, CC BY-SA