nutation

 
Pronunciation: /njuːˈteɪʃ(ə)n/

noun

[mass noun]
  • 1a periodic variation in the inclination of the axis of a rotating object.
  • Astronomy a periodic oscillation of the earth’s axis which causes the precession of the poles to follow a wavy rather than a circular path.
  • 2 Botany the circular swaying movement of the tip of a growing shoot.

Origin:

early 17th century (denoting nodding of the head): from Latin nutatio(n-), from nutare 'to nod'