From non- +‎ endogenous.

nonendogenous (not comparable)

1. Not endogenous.
   • 2015 July 14, Brett Silverstein, Jules Angst, “Evidence for Broadening Criteria for Atypical Depression Which May Define a Reactive Depressive Disorder”, in Psychiatry Journal‎^[1], volume 2015, →DOI:

     Further studies are called for as to whether the addition of these symptoms defines a nonendogenous reactive disorder (somatic depression) that is not simply a specifier of major depression but perhaps a separate nonendogenous disorder distinct from endogenous/melancholic depression.