Polymorphism (biology), having multiple alleles of a gene within a population, usually expressing different phenotypes;

Type polymorphism, allowing program code to work with various types

In sexology, polymorphous perversity

Polymorphism in object-oriented programming

Polymorphism (materials science), the ability of a solid material to exist in more than one form or crystal structure;

Polymorphic code, self-modifying program code designed to defeat anti-virus programs;

Polymorphism (biophysics) also referred to as Lipid polymorphism, the property of amphiphiles that gives rise to various aggregations of lipids;