The word "Zumological" is spelled with a "z" at the beginning because the sound it represents is the voiced alveolar fricative [z]. The "u" and "-mo-" in the middle are pronounced as a lax vowel [ʌ] and the "l" is pronounced as a voiced alveolar lateral approximant [l]. The "-ogical" at the end is spelled with "-ological" because it comes from the Greek root "-logos" meaning "study of." Therefore, "Zumological" refers to the study of a hypothetical substance called "zum."