(general) The ability to assume different forms or shapes.
(biology) The occurrence of more than one kind or form of organisms of the same species that exist together in one locality.
(chemistry) Crystallization of a compound in at least two distinct forms.
(biology) Polymorphism occurs when different phenotypes exist in the same population of a species. It is independent of sexual variations, and not connected by intermediate gradations but produced from common parents.
The most common example of polymorphism is sexual dimorphism in most higher organisms.
Word origin: From Ancient Greek poly (many) + morph (form) + -ism.
Related forms: polymorphic (adjective), polymorph (noun).
Related term: genetic polymorphism