Hundred proof is a term used to describe high alcohol content in beverages such as whiskey. However, if we look for antonyms, we can find a variety of words that signify something quite different. For example, the word 'sober' is an antonym for hundred proof, indicating a state of being calm, collected and free from intoxication. Similarly, 'weak' and 'watered-down' can signify the opposite of hundred proof, denoting something with a low alcohol content. Other antonyms may include words like 'mild,' 'gentle,' 'tame,' or even 'light.' Ultimately, the antonyms for hundred proof convey a sense of moderation, restraint, and a lack of potency.