—n. 1. a joint of a finger, esp. one of the articulations of a metacarpal with a phalanx.
2. the rounded prominence of such a joint when the finger is bent.
3. a joint of meat, consisting of the parts about the carpal or tarsal joint of a quadruped.
4. an angle or protrusion at the intersection of two members or surfaces, as in the timbers of a ship or in a roof.
5. See brass knuckles. 6. a cylindrical projecting part on a hinge, through which an axis or pin passes; the joint of a hinge.
7. (in a wire mesh) a bend in a wire crossing another wire.
8. (on a chair arm) one of the ridges left at the front end by longitudinal flutes carved to accommodate the fingers.
9. Naut.a pronounced edge formed by a change in the form of the shell of a hull.
—v.t. 1. to rub or press with the knuckles.
2. Marbles.to shoot (a marble) from the thumb and forefinger.
3. knuckle down, a. to apply oneself vigorously and earnestly; become serious: Just knuckle down for an hour or so and finish the work. b. Also,knuckle under.to submit; yield.