perspiration /pur′spirā″shən/ [L, per + spirare, to breathe] , 1. the act or process of perspiring; the excretion of fluid by the sweat glands through pores in the skin. 2. the fluid excreted by the sweat glands, consisting of water containing sodium chloride, phosphate, urea, ammonia, and other waste products. Perspiration serves as a mechanism for excretion and for regulation of body temperature. Abnormal amounts of perspiration usually result from organic causes but may also be precipitated by severe emotional stress. Also called sweat. Kinds include insensible perspiration, sensible perspiration. See also diaphoresis. −perspire, v.