The spelling of the word "biannuai" may seem tricky at first, but it can be easily explained through phonetic transcription. To start, the first syllable "bi-" is pronounced as /baɪ/ with the "i" sound as in "buy." The second syllable "-an-" is pronounced /æn/, with the "a" sound as in "apple." Finally, the last part "-uai" is pronounced as /weɪ/ with the "u" sound as in "you" and the "ai" combination as in "way." When put together, the correct spelling of the word is "biannuai."