The Collaborative International Dictionary of English v.0.48:

Gig \Gig\, n. [Cf. Icel. g[imac]gja fiddle, MHG. g[imac]ge, G.
   geige, Icel. geiga to take a wrong direction, rove at random,
   and E. jig.]
   1. A top or whirligig; any little thing that is whirled round
      in play.
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            Thou disputest like an infant; go, whip thy gig.
                                                  --Shak.
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   2. A light carriage, with one pair of wheels, drawn by one
      horse; a kind of chaise.
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   3. (Naut.) A long, light rowboat, generally clinkerbuilt, and
      designed to be fast; a boat appropriated to the use of the
      commanding officer; as, the captain's gig.
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   4. (Mach.) A rotatory cylinder, covered with wire teeth or
      teasels, for teaseling woolen cloth.
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   Gig machine, Gigging machine, Gig mill, or Napping
   machine. See Gig, 4.

   Gig saw. See Jig saw.
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The Collaborative International Dictionary of English v.0.48:

Jig \Jig\, n. [OF. gigue a stringed instrument, a kind of dance,
   F. gigue dance, tune, gig; of German origin; cf. MHG.
   g[imac]ge fiddle, G. geige. Cf. Gig a fiddle, Gig a
   whirligig.]
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   1. (Mus.) A light, brisk musical movement.
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            Hot and hasty, like a Scotch jig.     --Shak.
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   3. A light, humorous piece of writing, esp. in rhyme; a farce
      in verse; a ballad. [Obs.]
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            A jig shall be clapped at, and every rhyme
            Praised and applauded.                --Beau. & Fl.
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   4. A piece of sport; a trick; a prank. [Obs.]
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            Is't not a fine jig,
            A precious cunning, in the late Protector? --Beau. &
                                                  Fl.
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   5. A trolling bait, consisting of a bright spoon and a hook
      attached.
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   6. (Mach.)
      (a) A small machine or handy tool; esp.: (Metal Working) A
          contrivance fastened to or inclosing a piece of work,
          and having hard steel surfaces to guide a tool, as a
          drill, or to form a shield or template to work to, as
          in filing.
      (b) (Mining) An apparatus or a machine for jigging ore.
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   Drill jig, a jig for guiding a drill. See Jig, 6
      (a) .

   Jig drilling, Jig filing (Metal Working), a process of
      drilling or filing in which the action of the tool is
      directed or limited by a jig.

   Jig saw, a sawing machine with a narrow, vertically
      reciprocating saw, used to cut curved and irregular lines,
      or ornamental patterns in openwork, a scroll saw; --
      called also gig saw.
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