What was a monitor ship during the civil war?

The USS Monitor was an advance in ironclad warships in its time. It had a rotating turret on which a canon was mounted. It was part of the US Civil War sea battle at Hampton Roads. It fought against the CSS Virginia. This was the first battle between ironclad warships in history. The battle was a stand-off. The Moniter never fought again as it was lost in a sea storm some months later.