“Endogenous” is a term commonly used in biology to describe something with an internal cause or origin. If used in a social sciences capacity, it describes a trait found within a certain group or society. “Endogenous” is contrasted with “exogenous” — “endo” means “inside” and “exo” means “outside.” Paired with “-genous,” which means “producing or originating in,” these prefixes create words that describe whether something has an internal (“endogenous”) or external (“exogenous”) cause.