v.1. To check out formally from a job upon departure, especially by stamping the departure time on a timecard: If we punch out after 5:00, the company has to pay us for overtime.
2. To knock someone unconscious with a punch: The thief punched out the security guards and broke into the safe. He punched me out, and when I woke up, I was lying on the ground.
3. Slang To eject from a military aircraft: The pilots punched out just before the missile struck their plane.