The spelling of the word "most decalescent" is quite tricky as it is not a commonly used term. However, the correct pronunciation of this word can be broken down using IPA phonetic transcription. "Most" is pronounced as /məʊst/ and refers to the highest degree of something. "Decalescent" is pronounced as /dɛkəˈlɛsənt/ and refers to a substance that becomes hot and glows brightly. Therefore, "most decalescent" would mean something that is the hottest and emits the brightest glow.