"Endogenous" refers to something that originates from within a system or organism. In biology, it often describes processes or substances that are produced internally, such as hormones or enzymes. For example, insulin is an endogenous hormone produced by the pancreas to regulate blood sugar levels. In economics, "endogenous" can describe factors that are influenced by other variables within a model. For instance, economic growth can be considered endogenous if it is affected by factors like investment or education levels. This contrasts with "exogenous," which refers to influences coming from outside the system.