punching bag

punch·ing bag (pnchng)

n.

A stuffed or inflated leather bag that is usually suspended so that it can be punched with the fists for exercise.

Thesaurus

Noun	1.	punching bag - a person on whom another person vents their anger; "he resigned because his boss used him as a punching bag" victim - an unfortunate person who suffers from some adverse circumstance
	2.	punching bag - an inflated ball or bag that is suspended and punched for training in boxing punch bag, punchball, punching ball ball - round object that is hit or thrown or kicked in games; "the ball travelled 90 mph on his serve"; "the mayor threw out the first ball"; "the ball rolled into the corner pocket"