1. The act of nodding. So from the midmost the nutation spreads, round and more round, o'er all the sea of heads. (pope)
2. (Science: astronomy) A very small libratory motion of the earth's axis, by which its inclination to the plane of the ecliptic is constantly varying by a small amount.
3. (Science: botany) The motion of a flower in following the apparent movement of the sun, from the east in the morning to the west in the evening. Circumnutation.
Origin: L. Nutatio a nodding, fr. Nutare to nod: cf. F. Nutation.