the passage of gases through fine tubes because of differences in pressure or temperature
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the process of giving off or exhaling water vapor through the skin or mucous membranes
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the emission of water vapor from the leaves of plants
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Transpiration \Tran`spi*ra"tion\, 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.
2. (bot.) The evaporation of water, or exhalation of aqueous vapor, from cells and masses of tissue.
3. (Physics) The passing of gases through fine tubes, porous substances, or the like; as, transpiration through membranes.