Isomorphism, in mathematics, a mapping that preserves the structure

Isomorphism (sociology), a similarity of the processes or structure of one organization to those of another

Isomorphism (Gestalt psychology), a correspondence between a stimulus array and the brain state created by that stimulus

Isomorphism (biology), a similarity of form or structure between organisms

Isomorphism (computer science), a one-to-one relationship (usually: a bijection) between sets of entities

Cybernetic isomorphism, a recursive property of viable systems, as defined by Stafford Beer