Mousseau is a French surname that is pronounced as "moose-oh" in IPA phonetic transcription. The spelling of the word is derived from the French language, where "mousse" means "moss". The "au" at the end of the word is pronounced as a nasalized "oh" sound, which is common in the French language. Therefore, the correct spelling of this word is "Mousseau" and not "Mosso". It is essential to understand the correct spelling of a word to avoid confusion and miscommunication.