respiration

Respiration is taking a breath or the act of breathing. (noun)

An example of respiration is inhaling and exhaling air.

See respiration in Webster's New World College Dictionary

noun

act or process of respiring; breathing; inhaling and exhaling air
the processes by which a living organism or cell takes in oxygen from the air or water, distributes and utilizes it in oxidation, and gives off products of oxidation, esp. carbon dioxide
an analogous process in anaerobic organisms involving some substance other than free oxygen

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See respiration in American Heritage Dictionary 4

(rĕsˌpə-rāˈshən)

noun

a. The act or process of inhaling and exhaling; breathing. Also called ventilation.
b. The act or process by which an organism without lungs, such as a fish or plant, exchanges gases with its environment.
a. The oxidative process occurring within living cells by which the chemical energy of organic molecules is released in a series of metabolic steps involving the consumption of oxygen and the liberation of carbon dioxide and water.
b. Any of various analogous metabolic processes by which certain organisms, such as fungi and anaerobic bacteria, obtain energy from organic molecules.

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