polymorphism

polymorfia The ability to assume different forms or shapes.
puhekieltä The coexistence, in the same locality, of two or more distinct forms independent of sex, not connected by intermediate gradations, but produced from common parents.
puhekieltä The feature pertaining to the dynamic treatment of data elements based on their type, allowing for an instance of a method to have several definitions. (attention)
puhekieltä The property of certain typed formal systems of allowing for the use of type variables and binders/quantifiers over those type variables; likewise, the property of certain expressions (within such typed formal systems) of making use of at least one such typed variable.
puhekieltä The ability of a solid material to exist in more than one form or crystal structure; pleomorphism.
puhekieltä The regular existence of two or more different genotypes within a given species or population; also, variability of amino acid sequences within a gene's protein.
1999, (w), Genome, Harper Perennial 2004, p. 137:

Since 1990 they have found an entirely new role: they promise understanding of how and why our genes are all so different. They hold the key to human polymorphism.

Some polymorphisms can be quite stable – so stable that they span the change from an ancestral to a descendant species.