(mathematics) any set of points that satisfy a set of postulates of some kind
"assume that the topological space is finite dimensional"
An ordered pair (X, τ), where X is a set and τ, called the topology, is a collection of subsets of X which satisfies certain axioms and whose elements are called the open sets (or alternatively, for a different set of axioms, the closed sets);, (loosely) the set X.