[ tran-spuh-rey-shuhn ]
See synonyms for transpiration on
  1. an action or instance of transpiring.

  2. Botany. the passage of water through a plant from the roots through the vascular system to the atmosphere.

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Origin of transpiration

1545–55; trans- + Latin spīrātiōn-, stem of spīrātiō breathing (spīrāt(us), past participle of spīrāre to breathe + -iōn--ion); perhaps directly <French or New Latin

Words that may be confused with transpiration

Words Nearby transpiration Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use transpiration in a sentence

  • The remedy for this is to spray the leaves frequently so as to keep the air about them moist and so check transpiration.

    The First Book of Farming | Charles L. Goodrich
  • Warm dry air, especially when in motion, promotes the aeriform transpiration, by favouring evaporation.

    The Action of Medicines in the System | Frederick William Headland
  • These are,—the expired air, or the secretion of the air-cells of the lungs,—and the ordinary cutaneous transpiration.

    The Action of Medicines in the System | Frederick William Headland

Scientific definitions for transpiration


[ trăn′spə-rāshən ]

  1. The process of giving off vapor containing water and waste products, especially through the stomata on leaves or the pores of the skin.

a closer look

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.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.