Definition:Topological Property

Definition
Let $P$ be a property whose domain is the set of all topological spaces.

Suppose that whenever $P \left({T}\right)$ holds, then so does $P \left({T'}\right)$, where $T$ and $T'$ are topological spaces which are homeomorphic.

Then $P$ is known as a topological property or a topological invariant.

Loosely, a topological property is one which is preserved under homeomorphism.

Also see

 * Continuous invariant
 * Open invariant
 * Closed invariant