The word "katsuwonus" is a type of fish, also known as the skipjack tuna. The spelling of this word can be explained using the International Phonetic Alphabet (IPA). The first syllable "kat" is pronounced with a short "a" sound as in "cat". The "su" is pronounced with a short "u" as in "cup", and the "wo" is pronounced with a long "o" as in "bone". The final syllable "nus" is pronounced with a short "u" as in "cup". So the phonetic transcription of "katsuwonus" is /kætˈsuwənoʊs/.