(biology) 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.
(computer science) The feature of object-oriented programming pertaining to the dynamic treatment of data elements based on their type, allowing for an instance of a method to have several definitions.
(mathematics, type theory) The property of certain typedformal 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.
(crystallography) The ability of a solid material to exist in more than one form or crystal structure; pleomorphism.
(genetics) 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, Matt Ridley, 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.
2004, Richard Dawkins, The Ancestor's Tale, Phoenix 2005, p. 63:Some polymorphisms can be quite stable – so stable that they span the change from an ancestral to a descendant species.