n a small metal weapon; worn over the knuckles on the back of the hand
n a joint of a finger when the fist is closed
v press or rub with the knuckles
v shoot a marble while keeping one's knuckles on the ground
n. （指人）指关节( knuckle的名词复数 ); （指动物）膝关节, 踝
v. （指人）指关节( knuckle的第三人称单数 ); （指动物）膝关节, 踝