The spelling of the word "Bonaci" can be explained using the International Phonetic Alphabet (IPA). The first syllable "Bo" is pronounced with an open-o sound, as in "boat." The "n" is pronounced with a nasal sound, and the second syllable "a-ci" has a soft "a" sound followed by a "ch" sound as in "chair." Therefore, the correct IPA transcription is /bəʊˈnɑː.tʃi/. This spelling may vary based on differences in regional accent and pronunciation.