subset(redirected from Strict subset)
Also found in: Dictionary, Thesaurus.
A subset of a set A is any set each of whose elements belongs to A. For example, the set of all even numbers is a subset of the set of all integers. If the empty set is included among the sets, then by definition it is a subset of any other set. The set A itself and the empty set are sometimes called improper subsets, while the other subsets are called proper.