Biannual refers to an event occurring twice a year. It is synonymous with semiannual and should not be confused with biennial, which means occurring every two years.
Biennial events or occurrences are those that happen every two years, a frequency and timing different from bianual events which happen twice within a single year.
Semiannual refers to an event or action occurring twice a year, often at six-month intervals. It is synonymous with the term 'biannual.'
