Kitchen utensil with a metal hemisphere (approx. 0.5-3 cm) on one or both ends of a straight handle. With the ball cutter you can turn balls from potatoes, melon, root vegetables, butter, apples and cheese and remove cores from half apples or pears. Often it is combined with other kitchen utensils such as a butter cutter (1).
See also the bottleopener. [MOT]
(1) Eg. BRIDGE & TIBBETTS: 43.