object ball object ball /ˈɑbdʒɛkt bɔːl/

noun

1. The billiard ball that is intended to be the first ball struck by the cue ball  ( object ball )
   the billiard ball that is intended to be the first ball struck by the cue ball
    In our game of billiards, I focused on hitting the object ball accurately.
   In our game of billiards, I focused on hitting the object ball accurately.