The knuckles are the joints of the fingers, which are brought into prominence when the hand is shut. The word is derived from the diminutive of a word for bone, found in German Knochen. Medically, it is said that the knuckles are formed by the metacarpophalangeal and interphalangeal joints of the finger.
This term refers to an abrupt or hard edged change in the shape of a curve or a surface. The point at which the hard change is located is called a knuckle point or a breakpoint on the curve. For surfaces, a knuckle line or curve usually forms the hard edge between two surfaces. (Most people call this a chine!)
Any abrupt change in direction or non-tangency in any external structure of a vessel, forming a ' knuckle-line' i.e. the line formed at the apex of the angle dividing the upper and lower part of the stern or counter.
A casting at the outboard ends of the axles that the spindle / hub / wheel assembly connects to .Replacement knuckles are used on lifted IFS vehicles when the lower control arms are lowered, but the upper control arms are not.
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.