polymorphism vs polymorphous

polymorphism is a noun but polymorphous is not a noun.

Word	Noun	Adjective	Verb	Adverb
polymorphism	Yes	No	No	No
polymorphous	No	Yes	No	No

polymorphism (noun)	polymorphous (noun)
(biology) the existence of two or more forms of individuals within the same animal species (independent of sex differences)
(chemistry) the existence of different kinds of crystal of the same chemical compound
(genetics) the genetic variation within a population that natural selection can operate on

polymorphism (adjective)	polymorphous (adjective)
	relating to the occurrence of more than one kind of individual (independent of sexual differences) in an interbreeding population
	relating to the crystallization of a compound in two or more different forms
	having or occurring in several distinct forms