Exogenous \Ex*og"e*nous\, a. 1. (Bot.) Pertaining to, or having the character of, an exogen; -- the opposite of endogenous. 2. (Biol.) Growing by addition to the exterior. 3. (Anat.) Growing from previously ossified parts; -- opposed to {autogenous}. --Owen. {Exogenous aneurism} (Med.), an aneurism which is produced by causes acting from without, as from injury.