punching bag

punch·ing bag

 (pŭn′chĭng)n.1. A stuffed or inflated bag made of leather or other durable material that is either mounted on a stand or suspended at a height suitable for being punched or kicked for practice or exercise.2. A target of frequent criticism or abuse: "He ... became a punching bag for every comic's fat jokes" (Vanity Fair).

punch′ing bag`

n. an inflated or stuffed bag, usu. suspended, punched with the fists as an exercise. [1895–1900]

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 boxingpunch bag, punchball, punching ballball - 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"