late 14c., "heated till it glows red" (of metal, etc.); of persons, "lively, passionate," it is recorded from c.1600. Red-hot mama is 1926, jazz slang, "earthy female singer," also "girlfriend, lover."
Very hot; sizzling •An intensive of all slang senses of hot (1758+)
noun phraseA frankfurter; hot dog (1892+)