knuckle

Words with a similar base: knuckle, knuckle_joint

'knuckle'

[knuckle.n.01] as in: a joint of a finger when the fist is closed

'knuckle'

[knuckle.v.01] as in: press or rub with the knuckles

'knuckle'

[knuckle.v.02] as in: shoot a marble while keeping one's knuckles on the ground