AskDefine | Define exogenous

Dictionary Definition

exogenous adj : derived or originating externally [syn: exogenic] [ant: endogenous, endogenous]

User Contributed Dictionary



  1. produced or originating outside of an organism
  2. of a disease: having an external cause
  3. 1. of information: received from outside a group 2. descriptive of a group created by public as opposed to private information

Extensive Definition

Exogenous (or exogeneous) (from the Greek words "exo" and "gen", meaning "outside" and "production") refers to an action or object coming from outside a system. It is the opposite of endogenous, something generated from within the system.
  • In an economic model, an exogenous change is one that comes from outside the model and is unexplained by the model. For example, in the simple supply and demand model, a change in consumer tastes or preferences is unexplained by the model and also leads to endogenous changes in demand that lead to changes in the equilibrium price. Put another way, an exogenous change involves an alteration of a variable that is autonomous, i.e., unaffected by the workings of the model.
  • In linear regression, it means that the variable is independent of all other response values.
  • In biology, "exogenous" refers to an action or object coming from the outside of a system. For example, an exogenous contrast agent in medical imaging refers to a liquid injected into the patient intravenously that enhances visibility of a pathology, such as a tumor.
  • In Ludology, the study of games, exogenous refers to anything outside the game itself. Therefore an item in a Massive Multiplayer Online Game would have exogenous value if people were buying it with real world money rather than in game currency (though its in game cost would be endogenous).


  • Posner, M.I. (1980), Orienting of attention. Quarterly Journal of Experimental Psychology, 32: 3 – 25.
exogenous in Czech: Exogenní
exogenous in Norwegian Nynorsk: Eksogen
exogenous in Serbian: Егзогено
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