Added 10 October 2026 bi-annual adjective adjective ! Definition from Wiktionary (CC BY-SA). More about bi-annual at Wordnik → Where our words come from → Alternative spelling of biannual. Related Words: semiannualbiannualhalf-yearlybiennialquarterlysemi-annualtwo-yearsemestrialhalfyearlysemi-monthlybi-weeklysemi-yearly Back to today's word