Isomorphism or isomorph may refer to:

• Isomorphism, in mathematics, logic, philosophy, and information theory, a mapping that preserves the structure of the mapped entities, in particular:
  • Graph isomorphism a mapping that preserves the edges and vertices of a graph
  • Group isomorphism a mapping that preserves the group structure
  • Order isomorphism a mapping that preserves the comparabilities of a partially ordered set.
  • Ring isomorphism a mapping that preserves both the additive and multiplicative structure of a ring
  • Isomorphism theorems theorems that assert that some homomorphisms involving quotients and subobjects are isomorphisms
• Isomorphism (sociology), a similarity of the processes or structure of one organization to those of another
• Isomorphism (crystallography), a similarity of crystal form
• Isomorphism (Gestalt psychology), a correspondence between a stimulus array and the brain state created by that stimulus
• Cybernetic isomorphism, a recursive property of viable systems, as defined in Stafford Beer's viable system model
• Isomorph (gene), a classification of gene mutation

• Isomorph Records, a British music label