Source : Webster's Revised Unabridged Dictionary (1913)

Gyration \Gy*ra"tion\, n.
   1. The act of turning or whirling, as around a fixed center;
      a circular or spiral motion; motion about an axis;
      rotation; revolution.

            The gyrations of an ascending balloon. --De Quincey.

            If a burning coal be nimbly moved round in a circle,
            with gyrations continually repeated, the whole
            circle will appear like fire.         --Sir I.
                                                  Newton.

   2. (Zo["o]l.) One of the whorls of a spiral univalve shell.

   {Center of gyration}. (Mech.) See under {Center}.

   {Radius of gyration} the distance between the axis of a
      rotating body and its center of gyration. --Rankine.