pure water at mean atmosphere pressure at sea level if we’re getting technical, but frankly human body temperature varies from 35.5C (95.9F) to 37.5C (99.5F) anyway, and that’s before considering when people are ill, so if we go down that route it falls apart quickly enough that the definition of 100 given above is clearly just as arbitrary
Freezing point of pure water - but saltwater/brine freezes as a different temperature.
pure water at mean atmosphere pressure at sea level if we’re getting technical, but frankly human body temperature varies from 35.5C (95.9F) to 37.5C (99.5F) anyway, and that’s before considering when people are ill, so if we go down that route it falls apart quickly enough that the definition of 100 given above is clearly just as arbitrary