The Collaborative International Dictionary of English v.0.48:

Flounce \Flounce\, v. i. [imp. & p. p. Flounced (flounst); p.
   pr. & vb. n. Flouncing.] [Cf. OSw. flunsa to immerge.]
   To throw the limbs and body one way and the other; to spring,
   turn, or twist with sudden effort or violence; to struggle,
   as a horse in mire; to flounder; to throw one's self with a
   jerk or spasm, often as in displeasure.
   [1913 Webster]

         To flutter and flounce will do nothing but batter and
         bruise us.                               --Barrow.
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         With his broad fins and forky tail he laves
         The rising sirge, and flounces in the waves. --Addison.
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