Perspiration rate was the rate at which an individual perspired.
In 2266, during Harry Mudd's hearing, the perspiration rate of the men present in USS Enterprise's briefing room increased due to his lovely companions. This, among other symptoms, was detected when James T. Kirk asked Enterprise's computer to go to sensor probe. Embarrassed, he asked the computer to strike it from the record. (TOS: "Mudd's Women")