The spelling of the word "callison" can be explained using the International Phonetic Alphabet (IPA) transcription. The first syllable is pronounced as "kæl," which represents the "k" sound as in "cat" and "l" sound as in "like." The second syllable is pronounced as "ɪsən," which represents the "i" sound as in "bit," "s" sound as in "sit," and "ən" sound as in "button." Therefore, the correct spelling of this word is "callison" and its pronunciation is "kæl-ɪs-ən."