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. Zool. 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.
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