Exogen is a term that refers to a process or event that originates from outside the system. Synonyms for exogen include external, extrinsic, foreign, alien, and introduced. These words indicate that the object or the event is not naturally occurring in the system but is instead brought in from outside. Exogenous factors can have significant effects on a system, and it is often important to understand and account for them in analysis and decision-making. In many cases, exogenous factors can be sources of stress or disruption in a system, but they can also provide important inputs or opportunities for growth and development.