The spelling of the word "most substrative" can be explained using the IPA phonetic transcription. The word begins with /m/ which is a bilabial consonant, followed by a long /o/ vowel sound represented by /oʊ/. The next sound is /s/, a voiceless alveolar fricative, followed by /t/ which is an alveolar stop. The final syllable contains /s/, another voiceless alveolar fricative, and an unstressed /ɪv/ ending. This complex spelling is representative of the diverse sounds used in English language words.