Definition of subsets:
(n) :
A group of things or people, all of which are in a specified larger group.
(n) :
(set theory, of a set S) A set A such that every element of A is also an element of S.
(v) :
(transitive) To take a subset of.
(v) :
(transitive, computing, typography) To extract only the portions of (a font) that are needed to display a particular document.