Source : Webster's Revised Unabridged Dictionary (1913)

Whipsaw \Whip"saw`\, n.
   A saw for dividing timber lengthwise, usually set in a frame,
   and worked by two persons; also, a fret saw.

Whipsaw \Whip"saw`\, n.
   A kind of narrow ripsaw, tapering from butt to point, with
   hook teeth and averaging from 5 to 71/2 feet in length, used
   by one or two men.

Whipsaw \Whip"saw`\, v. t.
   1. To saw with the whipsaw.

   2. To defeat in, or cause to lose, two different bets at the
      same turn or in one play, as a player at faro who has made
      two bets at the same time, one that a card will lose and
      another that a different card will win; hence, to defeat
      in spite of every effort.

Source : WordNet®

whipsaw
     n : a handsaw intended for use by two people [syn: {two-handed
         saw}]
     v 1: victimize, especially in gambling or negotiations
     2: saw with a whipsaw
     [also: {whipsawn}]