|1.||(intr) to come to light; be known|
|2.||informal (intr) to happen or occur|
|3.||physiol to give off or exhale (water or vapour) through the skin, a mucous membrane, etc|
|4.||(of plants) to lose (water in the form of water vapour), esp through the stomata of the leaves|
|[C16: from Medieval Latin transpīrāre, from Latin |
|usage It is often maintained that transpire should not be used to mean happen or occur, as in the event transpired late in the evening, and that the word is properly used to mean become known, as in it transpired later that the thief had been caught. The word is, however, widely used in the former sense, esp in spoken English|
transpiration tran·spi·ra·tion (trān'spə-rā'shən)
The passage of watery vapor through the skin or through any membrane or pore.
|transpiration (trān'spə-rā'shən) Pronunciation Key
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The process of giving off vapor containing water and waste products, especially through the stomata on leaves or the pores of the skin.
Our Living Language : Plants need much more water than animals do. But why? Plants use water not only to carry nutrients throughout their tissues, but also to exchange gases with the air in the process known as transpiration. Air, which contains the carbon dioxide that plant cells need for photosynthesis, enters the plant mainly through the stomata (tiny holes under its leaves). The air travels through tiny spaces in the leaf tissue to the cells that conduct photosynthesis. These cells are coated with a thin layer of water. The cell walls do not permit gases to pass through them, but the carbon dioxide can move across the cell walls by dissolving in the water on their surface. The cells remove the carbon dioxide from the water and use the same water to carry out oxygen, the main waste product of photosynthesis. All this mixing of water and air in transpiration, though, has one drawback: more than 90 percent of the water that a plant's roots suck up is lost by evaporation through the stomata. This is why a plant always needs water and why plants that live in dry climates, such as cacti, have reduced leaf surfaces from which less water can escape.