- Closure (computer science): A feature in some computer programming languages that allows a procedure to bind to its environment, so that it may be called (and its internal variables utilized) from anywhere within the process, instead of using C-like scope rules to limit its availability.
- Closure (topology): A set together with all its limit points.
- Closure operator: An idempotent unary operator on subsets of a given set, mapping a set to a larger set with a particular property.
- : A field extension generated by the roots of all polynomials over the ground field.
- Integral closure: The ring of elements of an extension of a ring which satisfy a monic polynomial over the base ring.