The Collaborative International Dictionary of English v.0.48:

Basketball \Bas"ket*ball`\, n.
   1. A ball game, usually played indoors in an area called the
      basketball court, in which two opposing teams of five
      players each contest with each other to toss a large
      inflated ball (the basketball) into opposite goals
      (baskets) resembling baskets, each typically a cylindrical
      mesh suspended from a circular rim which is held ten feet
      above the court. A goal scored by passing the basketball
      through the basket may count from one to three points,
      depending on the situation in which it was thrown.

   Syn: basketball game.
        [Webster 1913 Suppl. WordNet 1.5 +PJC]

   2. The inflatable ball used in the game of basketball.
      [PJC]

WordNet (r) 3.0 (2006):

basketball
    n 1: a game played on a court by two opposing teams of 5
         players; points are scored by throwing the ball through an
         elevated horizontal hoop [syn: basketball, basketball
         game, hoops]
    2: an inflated ball used in playing basketball