[ pree-sesh-uhn ]
See synonyms for precession on
  1. the act or fact of preceding; precedence.

  2. Mechanics. the motion of the rotation axis of a rigid body, as a spinning top, when a disturbing torque is applied while the body is rotating such that the rotation axis describes a cone, with the vertical through the vertex of the body as axis of the cone, and the motion of the rotating body is perpendicular to the direction of the torque.

  1. Astronomy.

    • the slow, conical motion of the earth's axis of rotation, caused by the gravitational attraction of the sun and moon, and, to a smaller extent, of the planets, on the equatorial bulge of the earth.

Origin of precession

1300–50; <Late Latin praecessiōn- (stem of praecessiō) a going before, advance, equivalent to Latin praecess(us) (past participle of praecēdere to precede) + -iōn--ion; see cession

Other words from precession

  • pre·ces·sion·al, adjective

Words Nearby precession Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use precession in a sentence

  • This is due to what is known as "precession;" a slow movement of the axis upon which the earth rotates.

    The Astronomy of the Bible | E. Walter Maunder
  • Does the precession of the equinoxes have any effect upon the seasons or upon the climate of different parts of the earth?

    A Text-Book of Astronomy | George C. Comstock
  • Will the precession ever bring back the right ascensions and declinations to be again what they now are?

    A Text-Book of Astronomy | George C. Comstock
  • This slow movement forward of the goal-post is called precession—the precession of the equinoxes.

    Pioneers of Science | Oliver Lodge
  • Instruct the computer to discontinue precession operations that have been initiated.

    Where I Wasn't Going | Walt Richmond

British Dictionary definitions for precession


/ (prɪˈsɛʃən) /

  1. the act of preceding

  1. the motion of a spinning body, such as a top, gyroscope, or planet, in which it wobbles so that the axis of rotation sweeps out a cone

Origin of precession

C16: from Late Latin praecessiō a going in advance, from Latin praecēdere to precede

Derived forms of precession

  • precessional, adjective
  • precessionally, adverb

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for precession


[ prē-sĕshən ]

  1. The rotational motion of the axis of a spinning body, such as the wobbling of a spinning top, caused by torque applied to the body along its axis of rotation.

  2. The motion of this kind made by the Earth's axis, caused mainly by the gravitational pull of the Sun, Moon, and other planets. The precession of Earth's axis has a period of nearly 25,800 years, during which time the reference points on the equatorial coordinate system (the celestial poles and celestial equator) will gradually shift their positions on the celestial sphere.♦ The precession of the equinoxes is the slow westward shift of the autumnal and vernal equinoxes along the ecliptic, resulting from precession of the Earth's axis. See also nutation.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.