Definition:Totally Disconnected Space

A topological space is called totally disconnected if all connected components are singletons.

Equivalently, a topological space is totally disconnected if it contains no nondegenerate connected subsets, i.e. connected subsets containing more than one point.

Remark
Note that a topological space containing at most one element is both connected and totally disconnected.

Hence, the definition is sometimes applied only to spaces having at least two elements.