Most diaphoretic refers to something that causes excessive sweating or perspiration. The antonyms for the word "most diaphoretic" would be words that describe something that does not cause sweating. Words like "dry," "arid," "parched," "dehydrated," or "hot" may be used as antonyms for "most diaphoretic." In addition, "cool," "chilled," "temperate," or "cold" could also be considered antonyms since they describe temperatures that do not cause excessive sweating. Overall, antonyms for "most diaphoretic" would describe conditions or environments that are dry, not hot, or not conducive to sweating.