What does transpiration mean?
Transpiration usually denotes the process by which plants release water vapor into the atmosphere. Most of this loss occurs through stomata, tiny adjustable openings in the leaves, and it is essential to plant function because pulling water upward through the roots and stems helps deliver water and dissolved minerals to the leaves. Some of the water taken up by a plant escapes as vapor, while the remainder is used in growth and photosynthesis. The rate of transpiration varies with temperature, humidity, light, wind, soil moisture, and plant characteristics, making it an important subject in agriculture, forestry, and water conservation. In broader or older usage, transpiration can refer more generally to the outward passage or evaporation of moisture. The term is principally scientific and formal rather than everyday. It is also related to the movement of water through plants: transpiration from the leaves helps generate tension that draws water upward from the roots.
nounIn botany, transpiration is the process by which plants lose water vapor, mainly through tiny pores called stomata in their leaves. More broadly, it refers to the evaporation or outward release of moisture from a surface.
- The process by which plants lose water vapor, principally through stomata in their leaves.
- The broader process of moisture passing from or evaporating off a surface.
"The tree's transpiration increased as the hot afternoon made the soil dry."
"High temperatures and a dry soil can reduce a crop's rate of transpiration."
"Mist and condensation on a cold window represent forms of moisture movement opposite to transpiration."
The plural is uncommon because transpiration is usually discussed as a process rather than as a countable occurrence.
"The study compared the transpirations of several tree species."
Transpiration is a tree's invisible plumbing: water rises through the trunk and some of it escapes into the air through the leaves.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does transpiration come from?
The word comes through Late Latin from Latin transspirare, meaning “to breathe forth” or “to pass out through pores.” It combines trans-, indicating passage across or through, with spirare, “to breathe.” The noun entered English in the early modern period for the release of moisture and later became especially established in botanical terminology.
Related word forms
How transpiration is actually used
The word is formal and technical, especially in plant physiology, horticulture, and environmental science. It is not normally used as a general synonym for sweating.
Easily confused with transpiration
Perspiration is the process of producing sweat and its release from the body, whereas transpiration in modern usage usually concerns the loss of water vapor from plants.
Evaporation is the general change of liquid into vapor, while transpiration more specifically describes moisture released by a plant, chiefly through its stomata.