The Collaborative International Dictionary of English v.0.48:

Whirligig \Whirl"i*gig\, n. [Whirl + gig.]
   [1913 Webster]
   1. A child's toy, spun or whirled around like a wheel upon an
      axis, or like a top. --Johnson.
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   2. Anything which whirls around, or in which persons or
      things are whirled about, as a frame with seats or wooden
      horses.
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            With a whirligig of jubilant mosquitoes spinning
            about each head.                      --G. W. Cable.
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   3. A mediaeval instrument for punishing petty offenders,
      being a kind of wooden cage turning on a pivot, in which
      the offender was whirled round with great velocity.
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   4. (Zool.) Any one of numerous species of beetles belonging
      to Gyrinus and allied genera. The body is firm, oval or
      boatlike in form, and usually dark colored with a
      bronzelike luster. These beetles live mostly on the
      surface of water, and move about with great celerity in a
      gyrating, or circular, manner, but they are also able to
      dive and swim rapidly. The larva is aquatic. Called also
      weaver, whirlwig, and whirlwig beetle.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Whirlwig \Whirl"wig`\, n. [Cf. Earwig.] (Zool.)
   A whirligig.
   [1913 Webster]