The spelling of the word "Fennessey" is pronounced as /fɛn.ə.si/. It is a surname of Irish origin that means "descendant of Fionnseach". The word "Fionnseach" comes from the Irish Gaelic language and means "fair-haired warrior". It is important to note that the letter "e" sounds like "uh" in the middle of the word, which is why it is spelled with two "n"s and not just one. Proper spelling is essential in maintaining the correct pronunciation of words.