The word sack can refer to:
- In American football, a quarterback sack: the tackling of a quarterback behind the line of scrimmage, before he has had a chance to pass or hand off the ball.
- In the British Commonwealth (except Canada), to be terminated from one's job or workplace – equivalent to being fired in the U.S or Canada. i.e "He was sacked for stealing." or "He was fired for stealing." Also, "got fired", "got sacked", or "got the sack".
- An old name for sherry.
- The deliberate destruction of a city after invasion.
- A large bag, typically made of heavy cloth such as hemp or burlap.
- Any bag, such as a paper sack for a lunch, or a lunch sack instead of a lunch box.
- Slang for testes or scrotum.
- Sleeping - in the phrase "to hit the sack".