subset

noun

1. A set A such that every element of A is also an element of S.

   “The set of integers is a subset of the set of real numbers.”

   “The set #92;lbracea,b#92;rbrace is a both a subset and a proper subset of #92;lbracea,b,c#92;rbrace while the set #92;lbracea,b,c#92;rbrace is a subset of #92;lbracea,b,c#92;rbrace but not a proper subset of #92;lbracea,b,c#92;rbrace.”

   “1963, David B. MacNeil, Modern Mathematics for the Practical Man, David Van Nostrand, Republished as 2013, David B. MacNeil, Fundamentals of Modern Mathematics: A Practical Review, Dover, page 3, In the foregoing example, the set D of the first four letters of the alphabet, was a subset of the set A of all the letters of the alphabet, because A includes all the members of D.”

   “Let A be a subset of the topological space X and take x#92;inX.”

   “We say that a set S has a finite partition into subsets S#95;1,#92;dots,S#95;n, if S#61;S#95;i#92;cup#92;dots#92;cupS#95;n, where the subsets are pairwise disjoint, that is, S#95;i#92;capS#95;j#61;#92;empty, if i#92;nej. (We do not require that the subsets be nonempty.)”

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

   “We asked a subset of the population of the town for their opinion.”

verb

1. (transitive)To take a subset of.
2. (transitive)To extract only the portions of (a font) that are needed to display a particular document.