Endogenous variables in causal modeling are the variables with causal links (arrows) leading to them from other variables in the model. In other words, endogenous variables have explicit causes within the model.
The concept of endogenous variable is fundamental in path analysis and structural equation modeling.
The complementary concept is exogenous variable
Note: classification of a particular variable as endogenous depends on the chosen causal model: the same variable may be endogenous in one model and exogenous in another model based on the same set of variables.