The correct spelling of "most overseeing" is actually "most overseeing" with the stress on the second syllable. The word is pronounced as /moʊst ˌoʊvərˈsiːɪŋ/ according to the IPA phonetic transcription. The first syllable is pronounced as the same as in the word "most" and the second syllable is pronounced as "over-seeing" with the stress on the "see" sound. This word means to supervise or manage something or someone closely.