'brass knuckles' definitions:

Definition of 'brass knuckles'

noun

A small metal weapon; worn over the knuckles on the back of the hand [syn: brass knucks, knucks, brass knuckles, knuckles, knuckle duster]

From: GCIDE

knuckles \knuc"kles\ n. pl. a small metal weapon, worn over the knuckles on the back of the hand; called also brass knuckles and knuckle duster.
Syn: brass knucks, knucks, brass knuckles, knuckle duster. [WordNet 1.5]

From: GCIDE

Knuckle \Knuc"kle\, n. [OE. knokel, knokil, AS. cuncel; akin to D. knokkel, OFries. knokele, knokle, G. kn["o]chel, Sw. knoge, Dan. knokkel, G. knochen bone, and perh. to E. knock.]
1. The joint of a finger, particularly when made prominent by the closing of the fingers. --Davenant. [1913 Webster]
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. [1913 Webster]
With weary knuckles on thy brim she kneeled sadly down. --Golding. [1913 Webster]
3. The joint of a plant. [Obs.] --Bacon. [1913 Webster]
4. (Mech.) The joining parts of a hinge through which the pin or rivet passes; a knuckle joint. [1913 Webster]
5. (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. [1913 Webster]
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; -- called also knuckle duster, knuckles or brass knuckles. [Slang.] [1913 Webster]
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. [1913 Webster]