ex·og·e·nous / ekˈsäjənəs/ • adj. of, relating to, or developing from external factors.Often contrasted with endogenous. ∎  Biol. growing or originating from outside an organism: an exogenous hormone. ∎  chiefly Psychiatry (of a disease, symptom, etc.) caused by an agent or organism outside the body: exogenous depression. ∎  relating to an external group or society: exogenous marriage.

exogenous (ek-soj-in-ŭs) adj. originating outside the body or part of the body: applied particularly to substances in the body that are derived from the diet rather than built up by the body's own processes of metabolism. Compare endogenous.

exogenous Describing substances, stimuli, etc., that originate outside an organism. For example, vitamins that cannot be synthesized by an animal are said to be supplied exogenously in the diet. Compare endogenous.