The word "aitionastic" is spelled "ae-ti-o-nas-tic" using the International Phonetic Alphabet (IPA) transcription. The "ae" represents the vowel sound in "cat," while "ti" is pronounced as "sh" in "shampoo." "O" is pronounced as in "hot," "nas" as in "nasty," and "tic" as in "tick." This word describes something that relates to the cause or origin of something, often in a historical or mythical context. Its precise definition can vary based on its usage.