noun

1. the act of preceding; precedence
2. Astron. precession of the equinoxes
3. Mech. an effect exhibited by a spinning body, as a top, when an applied torque tends to change the direction of its rotational axis, causing this axis generally to describe a cone and to turn at right angles to the direction of the torque

Etymology: ME < LL praecessio < L praecedere, to precede