Submitting by tapping the mat or your opponent's body to signal you give up. In kayfabe, it's admitting you can't take the pain anymore. It's considered a less prestigious loss than a pinfall because you're choosing to quit. Some wrestlers have storylines built around refusing to tap — they pass out in the hold instead. Steve Austin passing out in the Sharpshooter at WrestleMania 13 is the most iconic non-tap in history.
"He tapped! He actually tapped! He said he'd never give up but the pain was too much."