verb

• (transitive) To incapacitate; especially by inducing disorientation or unconsciousness.
  "Bill tried to stun the snake by striking it on the head."
• (transitive) To shock or surprise.
  "The celebrity was stunned to find herself confronted with unfounded allegations on the front page of a newspaper."
• (snooker, billiards) To hit the cue ball so that it slides without topspin or backspin (and with or without sidespin) and continues at a natural angle after contact with the object ball
• (intransitive, video games) To enter a stunned state.
  "The monsters stun when you jump on them."

noun

• (Newfoundland) A person who lacks intelligence.
• (billiards, snooker, pool) The effect on the cue ball where the ball is hit without topspin, backspin or sidespin.
  "Williams will need a lot of stun to avoid going in the middle pocket"
• (science fiction, uncountable) A low-range setting for an energy weapon that will stun its target but not injure or kill it.
  "Captain James Kirk: "Set your phaser on one quarter. I'll leave mine on stun.""