The spelling of the word "Kathyline" can be explained using the International Phonetic Alphabet (IPA) transcription. The first syllable is pronounced as "kæt" with a short "a" sound, followed by the "ee" sound represented by the symbol "i" in IPA. The third syllable is pronounced as "line" with a long "i" sound represented by the symbol "aɪ" in IPA. Therefore, the correct spelling of this word would be "Kathyline", which is pronounced as "kætiːlaɪn."