subset

A set contained within a set.

In mathematics, a proper part or the whole of the set: thus, a subset of S is a set every element of which belongs to S.

With respect to another set, a set such that each of its elements is also an element of the other set.

A group of things or people, all of which are in a specified larger group.

a set whose members are members of another set; a set contained within another set