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Meaning of tourbillion

tour•bil•lion

Pronunciation: (toor-bil'yun), [key]
— n.
  1. a whirlwind or something resembling a whirlwind.
  2. a firework that rises spirally.
  3. a frame for the escapement of a timepiece, esp. a watch, geared to the going train in such a way as to rotate the escapement about once a minute in order to minimize positional error. Cf. karrusel.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.