Definition of "knuckle"

Any of the joints between the bones of the fingers.  examples

(by extension) A mechanical joint.  examples

(sports, billiards, snooker, pool) The curved part of the cushion at the entrance to the pockets on a cue sports table.  examples

The kneejoint of a quadruped, especially of a calf; formerly, the kneejoint of a human being.  quotations  examples

A cut of meat of various kinds.  examples

(obsolete) The joint of a plant.  quotations

(shipbuilding) A convex portion of a vessel's figure where a sudden change of shape occurs, as in a canal boat, where a nearly vertical side joins a nearly flat bottom.  examples

A contrivance, usually of brass or iron, and furnished with points, worn to protect the hand, to add force to a blow, and to disfigure the person struck; a knuckle duster.  examples

(skiing, snowboarding) The rounded point where a flat changes to a slope on a piste.  examples

(transitive) To apply pressure, or rub or massage with one's knuckles (sense 1).  examples

(transitive, slang) To strike or punch.  quotations

(intransitive) To bend the fingers.  examples

(intransitive) To touch one's forehead as a mark of respect.  examples

(intransitive, figurative) To yield.  examples

(snowboarding, skiing) To land on the knuckle (sense 9) of a curve of a slope, after a jump off a ramp that precedes the slope.  examples