Gyration /(jī̇*rā"shŭn)/

Gy·ra·tion

Gyration

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.
    If a burning coal be nimbly moved round in a circle, with gyrations continually repeated, the whole circle will appear like fire.
  2. One of the whorls of a spiral univalve shell. (Zool.)

Phrases & Compounds
Center of gyration
See under Center.
Radius of gyration
the distance between the axis of a rotating body and its center of gyration.