From Greek exo, meaning "outside", and the suffix -genous; refers to an action or object located outside of something or originating through external causes.

For example, structural inclusions occurring due to contaminations in the material are referred to as exogenous if they have entered the casting from the outside, i.e. through incorrect melting.Moreover, solidification is referred to as exogenous (s. Solidification type, Solidification morphology) if it proceeds from the outside, i.e. from the mold wall in inward direction (for example in flake graphite cast iron).

In contrast to that: endogenous.