[ nju:'teɪʃ(ə)n ]
■ noun
1》 a periodic variation in the inclination of an axis of rotation, especially that causing the earth's precession to follow a wavy rather than a circular path.
2》 Botany the circular swaying movement of the tip of a growing shoot.
Origin
C17 (denoting nodding of the head): from L. nutatio(n-) , from nutare 'to nod'.