Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
biannually is an adverb meaning "twice a year". It carries one recorded sense.
twice a year
“we hold our big sale biannually”
Definitions, synonyms and semantic relations for biannually come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.