1. A game in which jackstones are thrown and picked up in various groups between bounces of a small rubber ball
   "Knucklebones is an ancient game that has evolved into modern jacks";
   - jacks, jackstones

1. A bone that forms a knuckle
   "Children used to play games with sheep knucklebones"

Type of: bone, child's game, os[2]

Encyclopedia: Knucklebones