ball

Concise Oxford English Dictionary © 2008 Oxford University Press:
ball1

▶noun

• 1 a solid or hollow sphere, especially one that is kicked, thrown, or hit in a game.

  ■ a game played with a ball, especially (N. Amer.) baseball.

• 2 a single throw or kick of the ball in a game.

  ■ Cricket a delivery of the ball by the bowler to the batsman.

  ■ Baseball a pitch delivered outside the strike zone which the batter does not attempt to hit.

▶verb

• 1 squeeze or form into a ball.

• 2 N. Amer. vulgar slang (of a man) have sex with.

• 3 Brit. (of a flower) fail to open properly, decaying in the half-open bud.

– phrases
the ball is in your court it is up to you to make the next move.
the ball of the foot the rounded protuberant part of the foot at the base of the big toe.
the ball of the thumb the rounded protuberant part of the hand at the base of the thumb.
keep the ball rolling maintain the momentum of an activity.
keep one's eye on (or take one's eye off) the ball keep (or fail to keep) one's attention focused on the matter in hand.
on the ball alert to new ideas and methods.
play ball informal cooperate.
start (or get or set) the ball rolling make a start.
the whole ball of wax N. Amer. informal everything.

– derivatives
baller noun.

– origin ME: from ON bǫllr, of Gmc origin.

Concise Oxford English Dictionary © 2008 Oxford University Press:
ball2

▶noun a formal social gathering for dancing.

– phrases
have a ball informal enjoy oneself greatly.

– origin C17: from Fr. bal ‘a dance’.