[mass noun](Physics)the slow movement of the axis of a spinning body around another axis due to a torque (such as gravitational influence) acting to change the direction of the first axis. It is seen in the circle slowly traced out by the pole of a spinning gyroscope (物理)进动,旋进
派生 precess verb precessional adjective 语源
late 16th cent. (as a term in astronomy, referring to the precession of the equinoxes): from late Latin praecessio(n-), from praecedere 'go before' (see precede)