endogenous
Having an internal cause or origin.
Adjective
This term is primarily used in scientific, medical, and economic contexts to describe a process that starts from within a system rather than being triggered by an external stimulus. It carries a clinical, precise tone and is almost never used in casual conversation. In biology, it refers to substances produced inside an organism, such as hormones.
In economics, an endogenous variable is one that is determined by the internal logic of the model being studied. It creates a sharp contrast with exogenous factors, which are treated as independent "shocks" coming from the outside world.