The phrase "exogenous source" refers to something that comes from outside or external to a particular entity or system. It means that the source is not inherent or originating from within that entity or system. Full definition
Several previous studies have relied on religious affiliation and the proximity to Catholic schools as exogenous sources of variation for identifying the effect of Catholic schooling on a wide (semanticscholar.org)
It can come from our own belly fat or food, whereas carbs can only be derived from exogenous sources. (siimland.com)
As a diabetic, I do tend to have more advanced glycation end products accumulating so eliminating animal products as a prime exogenous source was important. (nutritionfacts.org)