Source : Webster's Revised Unabridged Dictionary (1913)

Billiard \Bil"liard\, a.
   Of or pertaining to the game of billiards. ``Smooth as is a
   billiard ball.'' --B. Jonson.

Source : WordNet®

billiard
     adj : of or relating to billiards; "a billiard ball"; "a billiard
           cue"; "a billiard table"