pre·ces·sion

[pree-sesh-uhn]
noun
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.
3.
Astronomy.
a.
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.
b.
precession of the equinoxes.
Origin:
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

Related forms
pre·ces·sion·al, adjective
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2013.
Cite This Source Link To precession
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Precession is always a great word to know.
So is gobo. Does it mean:
a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison.
a screen or mat covered with a dark material for shielding a camera lens from excess light or glare.
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Collins
World English Dictionary
precession (prɪˈsɛʃən) [Click for IPA pronunciation guide]
 
—n
1.  the act of preceding
2.  See precession of the equinoxes
3.  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
 
[C16: from Late Latin praecessiō a going in advance, from Latin praecēdere to precede]
 
pre'cessional
 
—adj
 
pre'cessionally
 
—adv

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Etymonline
Word Origin & History

precession
1594, from L.L. præcissionem (nom. præcissio) "a coming before," from L. præcessus, pp. of præcedere (see precede). Originally used of calculations of the equinoxes, which come slightly earlier each year.
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Science Dictionary
precession   (prē-sěsh'ən)  Pronunciation Key 

  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 © 2002. Published by Houghton Mifflin. All rights reserved.
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Example sentences
It is a little fuzzy due to precession and the periodic station-keeping to correct that precession.
The reason the motorcycle behaves as you describe at speed is due to a phenomena called precession.
The direction of precession depends on the direction the wheel is spinning, not the hemisphere.
Because of precession, this point moves back slowly along the ecliptic.
Image for precession
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