Nutation

Webster's Dictionary of the English Language

·noun Circumnutation.

II. Nutation ·noun The act of Nodding.

III. Nutation ·noun 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.

IV. Nutation ·noun 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.