The phrase "most upon" is not a commonly used term in English, and may be considered archaic. However, the spelling of this phrase may be better understood using the International Phonetic Alphabet. The first word "most" is pronounced as /moʊst/, with a long "o" sound and a soft "s" sound. The second word "upon" is pronounced as /əˈpɑn/, with an unstressed "u" sound and a stressed "o" sound. Together, the phrase is pronounced as /moʊst əˈpɑn/.