Definition:Irreducible Component

Definition
Let $X$ be a topological space.

A subspace $Y \subset X$ is an irreducible component :
 * $Y$ is irreducible
 * $Y$ is not a proper subset of an irreducible subspace of $X$.

That is, $Y$ is maximal in the ordered set of irreducible subspaces of $X$, ordered by inclusion.

Also see

 * Point is Contained in Irreducible Component
 * Irreducible Component is Closed