The Collaborative International Dictionary of English v.0.48:
Gyration \Gy*ra"tion\ (j[-i]*r[=a]"sh[u^]n), n.
1. The act of turning or whirling, as around a fixed center;
a circular or spiral motion; motion about an axis;
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.
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.