(sports) A person, usually male, responsible for retrieving balls from the area of play, and returning them to the players.

(sports) A female responsible for getting the balls from off the area of play to the players.

plural of ball washer

(US, idiomatic, vulgar) A person or task which is excessively demanding or punishing.

(softball) A non-varsity softball team, typically played by youths (usually girls) under the age of 18. Frequently played in small cities and towns, sponsored by a local business and coached by volunteers.

(slang, vulgar) The scrotum.

(idiomatic) To fail in one's responsibilities or duties, or to make a mistake, especially at a critical point or when the result is very negative.

plural of ball boy

pinball (the game) / pinball (the ball)

(tennis) A machine that shoots tennis balls out of a pipe, allowing a player to practise hitting them.