Stunning Spell

The Stunning Spell (incantation Stupefy) is a spell that knocks the victim unconscious. The countercurse is Enervate. The spell will eventually wear off, even if the countercurse is not used. It is first used in Harry Potter and the Goblet of Fire when Harry Potter is preparing for the Third Task of the Triwizard Tournament.

"Stupefy" comes from the Latin "stupere", which means "to be struck senseless".