Source : Webster's Revised Unabridged Dictionary (1913)

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.

Source : WordNet®

exogenous
     adj : derived or originating externally [syn: {exogenic}] [ant: {endogenous},
            {endogenous}]