What is the meaning of Stunner?

Anything that is stunning.

1. A woman or man of stunning beauty or handsomeness , a knockout.

   A woman or man of stunning beauty or handsomeness , a knockout.

   A professional wrestling maneuver in which an attacking wrestler applies a facelock to an opponent and falls to a seated position, forcing the opponent's jaw or neck to drop on the attacker's shoulder.

   A pistol firing a beam capable of stunning an enemy.

   A person or machine that stuns an animal before slaughter.

   Source: wiktionary.org