knuckle

noun

1. Any of the joints between the bones of the fingers.
2. (broadly)A mechanical joint.
3. The curved part of the cushion at the entrance to the pockets on a cue sports table.
4. The kneejoint of a quadruped, especially of a calf; formerly, the kneejoint of a human being.

   “With wearie knockles on thy brim she kneeled sadly downe”

5. A cut of meat of various kinds.

   “Beef knuckle is from the knee joint. Pork knuckle, or ham hock, is from the joint between the tibia/fibula and the metatarsals of the foot of a pig, where the foot was attached to the leg.”

6. (obsolete)The joint of a plant.

   “In the West Indies there are found, even in sandy deserts and very dry places, large canes, which at every joint or knuckle yield a good supply of fresh water”

7. 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.
8. 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.

   “brass knuckles”

9. The rounded point where a flat changes to a slope on a piste.

verb

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

   “He knuckled the sleep from his eyes.”

2. (slang, transitive)To strike or punch.

   “I could feel my big toe snap, but as he's gone down on his good knee and half swung round I knuckled him in the kidney as hard as I could hit. He's gone all the way down, so I dropped my 19 stone into the middle of his back.”

   “Only then I knuckled him. He had to be taught a hard lesson.”

3. (intransitive)To bend the fingers.
4. (intransitive)To touch one's forehead as a mark of respect.
5. (figuratively, intransitive)To yield.
6. To land on the knuckle (noun sense 9) of a curve of a slope, after a jump off a ramp that precedes the slope.