Source : Webster's Revised Unabridged Dictionary (1913)

Wrench \Wrench\ (r[e^]nch), n. [OE. wrench deceit, AS. wrenc
   deceit, a twisting; akin to G. rank intrigue, crookedness,
   renken to bend, twist, and E. wring. [root]144. See {Wring},
   and cf. {Ranch}, v. t.]
   1. Trick; deceit; fraud; stratagem. [Obs.]

            His wily wrenches thou ne mayst not flee. --Chaucer.

   2. A violent twist, or a pull with twisting.

            He wringeth them such a wrench.       --Skelton.

            The injurious effect upon biographic literature of
            all such wrenches to the truth, is diffused
            everywhere.                           --De Quincey.

   3. A sprain; an injury by twisting, as in a joint.

   4. Means; contrivance. [Obs.] --Bacon.

   5. An instrument, often a simple bar or lever with jaws or an
      angular orifice either at the end or between the ends, for
      exerting a twisting strain, as in turning bolts, nuts,
      screw taps, etc.; a screw key. Many wrenches have
      adjustable jaws for grasping nuts, etc., of different
      sizes.

   6. (Mech.) The system made up of a force and a couple of
      forces in a plane perpendicular to that force. Any number
      of forces acting at any points upon a rigid body may be
      compounded so as to be equivalent to a wrench.

   {Carriage wrench}, a wrench adapted for removing or
      tightening the nuts that confine the wheels on the axles,
      or for turning the other nuts or bolts of a carriage or
      wagon.

   {Monkey wrench}. See under {Monkey}.

   {Wrench hammer}, a wrench with the end shaped so as to admit
      of being used as a hammer.