The spelling of the word "most sweetheart" is fairly straightforward. "Most" is spelled M-O-S-T and means "almost all" or "very." "Sweetheart" is spelled S-W-E-E-T-H-E-A-R-T and refers to a term of endearment for a loved one or a person who is kind and considerate. In phonetic transcription, "most" is /moʊst/ and "sweetheart" is /ˈswiːt.hɑːrt/. When combined, the word is pronounced as /məʊst ˈswiːt.hɑːrt/.