The word "boonest" is not a commonly used term in English. It can be spelled phonetically as /ˈbuːnɪst/ where the first two letters 'bo' are pronounced as in 'boot' and the 'oo' sound continues in the next syllable. The last syllable 'nest' is pronounced as in 'best'. There may be regional variations in the exact pronunciation of this word. However, it is important to note that the correct spelling of the word 'bonniest' refers to someone or something that is attractive or beautiful.