n(y)üˈtāshən noun
( -s )
Etymology: Latin nutation-, nutatio, from nutatus (past participle of nutare to nod, sway, rock, freq. of nuere to nod) + -ion-, -io -ion — more at numen
1. : the act of nodding ; especially : an involuntary nodding of the head
2. : a small inequality in the motion of precession : a libratory motion of the earth's axis like the nodding of a top due to joint action of the sun and moon by which its inclination to the plane of the ecliptic varies with a period of about 19 years and with a range of only a few seconds of arc so that the celestial poles describe wavy rather than circular parallels round the poles of the ecliptic
3. : a more or less rhythmical change in the position of growing plant organs due to variation in growth rates on different sides of the growing apex : an autonomic movement — compare circumnutation
4. : the vibratory displacement of the axis of a precessing top or gyroscope from the cone-shaped figure traced by the axis during precession