From HomoExcelsior

1. The act or state of preceding; precedence. 2. The motion of the axis of a spinning body, such as the wobble of a spinning top, when there is an external force acting on the axis. 3. Precession of the equinoxes. 4. A slow gyration of Earth's axis around the pole of the ecliptic, caused mainly by the gravitational pull of the sun, moon, and other planets on Earth's equatorial bulge.

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