knuckle
nounThe prominence of the dorsal aspect of a joint of a finger, especially of one of the joints connecting the fingers to the hand.
nounA rounded protuberance formed by the bones in a joint.
nounA cut of meat centering on the carpal or tarsal joint, as of a pig.
nounThe part of a hinge through which the pin passes.
nounA sharp angle formed by the meeting of two surfaces, especially two ship’s timbers.
nounBrass knuckles.
transitive verbTo press, rub, or hit with the knuckles.
transitive verbTo shoot (a marble) with the thumb over the bent forefinger.
phrasal verbTo apply oneself earnestly to a task.