biannual

Biannual is an English adjective and adverb that can have two common meanings. It can describe something occurring twice within a single year, or something occurring every two years. The ambiguity arises from the combination of the prefix bi- (two) and annual (year). Because of this dual sense, some dictionaries and style guides treat biannual as ambiguous and recommend clearer terms.

To avoid confusion, many writers distinguish the senses explicitly. The term semiannual is commonly used for twice-yearly occurrences, while biennial refers to something that happens every two years. Examples: a conference held semiannually; a festival that is biennial. If biannual is used, the time frame should be stated to eliminate ambiguity, such as “the report is published biannually in January and July” or “the council meets biannually, every six months.”

Originating from Latin, bi- meaning two and annual meaning year, biannual reflects a two-year or two-times-per-year concept. In practice, the term’s meaning can differ by region or publication, so precision is valued in formal writing. When exact timing matters, specifying the frequency (twice per year vs. every two years) avoids misinterpretation.