- 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. - The evaporation of water, or exhalation of aqueous
vapor, from cells and masses of tissue. - The passing of gases through fine tubes, porous
substances, or the like; as, transpiration through membranes.