- the act of respiring; inhalation and exhalation of air; breathing.
- Biology.
- the sum total of the physical and chemical processes in an organism by which oxygen is conveyed to tissues and cells, and the oxidation products, carbon dioxide and water, are given off.
- an analogous chemical process, as in muscle cells or in anaerobic bacteria, occurring in the absence of oxygen.
- the process in living organisms of taking in oxygen from the surroundings and giving out carbon dioxide (external respiration). In terrestrial animals this is effected by breathing air
- the chemical breakdown of complex organic substances, such as carbohydrates and fats, that takes place in the cells and tissues of animals and plants, during which energy is released and carbon dioxide produced (internal respiration)
