n. [ F. transpiration. ] 1. (Physiol.) The act or process of transpiring or excreting in the form of vapor; exhalation, as through the skin or other membranes of the body; as, pulmonary transpiration, or the excretion of aqueous vapor from the lungs. Perspiration is a form of transpiration. Cudworth. [ 1913 Webster ]
2. (bot.) The evaporation of water, or exhalation of aqueous vapor, from cells and masses of tissue. [ 1913 Webster ]
3. (Physics) The passing of gases through fine tubes, porous substances, or the like; as, transpiration through membranes. [ 1913 Webster ]