Source : Webster's Revised Unabridged Dictionary (1913)

Wrest \Wrest\, n.
   1. The act of wresting; a wrench; a violent twist; hence,
      distortion; perversion. --Hooker.

   2. Active or moving power. [Obs.] --Spenser.

   3. A key to tune a stringed instrument of music.

            The minstrel . . . wore round his neck a silver
            chain, by which hung the wrest, or key, with which
            he tuned his harp.                    --Sir W.
                                                  Scott.

   4. A partition in a water wheel, by which the form of the
      buckets is determined.

   {Wrest pin} (Piano Manuf.), one of the pins around which the
      ends of the wires are wound in a piano. --Knight.

   {Wrest plank} (Piano Manuf.), the part in which the wrest
      pins are inserted.