Developing from a deep- seated layer.
- A dictionary of scientific terms. By Henderson, I. F.; Henderson, W. D. Published 1920. (adjective) (adj.) (adjective)
Belonging to the endogens; of the nature of endogens, which increase in the stem by internal growth; originating by spontaneous effort from within.
- Nuttall's Standard dictionary of the English language. By Nuttall, P.Austin. Published 1914. (adjective) (adj.) (adjective)
Increasing by internal growth.
- Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874. (adjective) (adj.) (adjective)
Increasing like endogens, or by internal growth.
- The american dictionary of the english language. By Daniel Lyons. Published 1899. (adjective) (adj.) (adjective)

Usage examples:

As the same endogenous rock manifests almost every where the same degree of activity, so on the contrary, different rocks belonging to the same class, whether to the endogenous or the erupted, exhibit great differences in their character.
- COSMOS: A Sketch of the Physical Description of the Universe, Vol. 1 by Alexander von Humboldt
And it is not till Cainozoic times that we have the endogenous grasses and palms and angiospermous exogens.
- Creation and Its Records by B.H. Baden-Powell
They differ from the genuine epilepsy by the absence of the characteristic dementia, of attacks of petit mal, and by the fact that the seizures are never purely endogenous in origin.
- Studies in Forensic Psychiatry by Bernard Glueck