The spelling of the word "massini" can be explained using the International Phonetic Alphabet (IPA) transcription. The first syllable sounds like "mahs" with a short "a" sound and a soft "s" at the end. The second syllable is pronounced as "see" with a long "i" sound. The final syllable is pronounced as "nee" with a silent "n" and a long "ee" sound. Therefore, the correct spelling of the word is "massini" and is pronounced as /mɑːs.siː.niː/.