In general, polymorphism describes multiple possible states for a single property (it is said to be polymorphic).

Polymorphism can be:

• In materials science polymorphism is the ability of a solid material to exist in more than one form or crystal structure. Diamond, graphite and the Buckyball are examples of polymorphs of carbon. α-ferrite, austenite, and δ-ferrite are polymorphs of iron. When found in elemental solids the condition is also called Allotropy.
• In biology multiple alleles of a gene within a population, usually expressing different phenotypes, are called polymorphism. For instance, human skin color is polymorphic. See polymorphism (biology). Polymorphism in biology can also refer to single nucleotide polymorphisms.
• In computer programming, polymorphism is enabling operations to accept arguments of varying types.
• In computer underground terms, Polymorphic code is self-modifying code designed to defeat antivirus programs.