2. The kneejoint, or middle joint, of either leg of a quadruped, especially of a calf; — formerly used of the kneejoint of a human being. With weary knuckles on thy brim she kneeled sadly down. Golding.

3. The joint of a plant. [Obs.] Bacon.

4. (Mech.)

Defn: The joining pars of a hinge through which the pin or rivet passes; a knuckle joint.

5. (Shipbuilding)

Defn: 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.

6. 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; as, brass knuckles; — called also knuckle duster. [Slang.] Knuckle joint (Mach.), a hinge joint, in which a projection with an eye, on one piece, enters a jaw between two corresponding projections with eyes, on another piece, and is retained by a pin which passes through the eyes and forms the pivot. — Knuckle of veal (Cookery), the lower part of a leg of veal, from the line of the body to the knuckle.

KNUCKLE
Knuc"kle, v. i. [imp. & p. p. Knuckled;; p. pr. & vb. n. Knuckling.]

Defn: To yield; to submit; — used with down, to, or under. To knuckle to. (a) To submit to in a contest; to yield to. [Colloq.] See To knock under, under Knock, v. i. (b) To apply one's self vigorously or earnestly to; as, to knuckle to work. [Colloq.]

KNUCKLE
Knuc"kle, v. t.