Perspiration: 1) The secretion of fluid by the sweat (sudoriferous) glands. These small, tubular glands are situated within the skin, as well as in the subcutaneous tissue under it. They discharge their fluid through tiny openings in the surface of the skin. Perspiration serves at least two purposes: the removal of waste products such as urea and ammonia, and cooling of the body temperature as sweat evaporates. 2) The transparent, colorless, acidic fluid secreted by the sweat glands. It contains some fatty acids and mineral matter. Adult perspiration gains its characteristic odor from the waste products excreted. Also known as sweat.