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nutation

 - 5 dictionary results

nu⋅ta⋅tion

  [noo-tey-shuhn, nyoo-]
Use nutation in a Sentence
–noun
1. an act or instance of nodding one's head, esp. involuntarily or spasmodically.
2. Botany. spontaneous movements of plant parts during growth.
3. Astronomy. the periodic oscillation observed in the precession of the earth's axis and the precession of the equinoxes.
4. Mechanics. the variation of the inclination of the axis of a gyroscope to the vertical.
Origin:
1605–15; < L nūtātiōn- (s. of nūtātiō), equiv. to nūtāt(us) (ptp. of nūtāre to nod repeatedly; nū- nod + -tā- freq. suffix + -tus ptp. ending) + -iōn- -ion; cf. numen

Related forms:
nu⋅ta⋅tion⋅al, adjective
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
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nu·ta·tion   (nōō-tā'shən, nyōō-)   
n.  

  1. The act or an instance of nodding the head.

  2. A wobble in a spinning gyroscope or other rotating body.

  3. Astronomy A small periodic motion of the celestial pole of the earth with respect to the pole of the ecliptic.

  4. Botany A slight curving or circular movement in a stem, as of a twining plant, caused by irregular growth rates of different parts.


[Latin nūtātiō, nūtātiōn-, from nūtātus, past participle of nūtāre, frequentative of -nuere, to nod.]
nu·ta'tion·al adj.
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Medical Dictionary

nutation nu·ta·tion (n&oomacr;-tā'shən, ny&oomacr;-)
n.
The act of nodding the head, especially involuntarily.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Science Dictionary
nutation   (n-tā'shən)  Pronunciation Key 

  1. A small, cyclic variation of the Earth's axis of rotation with a period of 18.6 years, caused by tidal forces (mostly due to the gravity of the Moon). Nutation is a small and relatively rapid oscillation of the axis superimposed on the larger and much slower oscillation known as precession. Although discovered in 1728 by the British astronomer James Bradley (1693-1762), nutation was not explained until two decades later.

  2. A slight curving or circular movement in a stem, as of a twining plant, caused by irregular growth rates of different parts.


The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia

nutation

in astronomy, a small irregularity in the precession of the equinoxes. Precession is the slow, toplike wobbling of the spinning Earth, with a period of about 26,000 years. Nutation (Latin nutare, "to nod") superimposes a small oscillation, with a period of 18.6 years and an amplitude of 9.2 seconds of arc, upon this great slow movement. The cause of nutation lies chiefly in the fact that the plane of the Moon's orbit around the Earth is tilted by about 5 from the plane of the Earth's orbit around the Sun. The Moon's orbital plane precesses around the Earth's in 18.6 years, and the effect of the Moon on the precession of the equinoxes varies with this same period. The British astronomer James Bradley announced his discovery of nutation in 1748.

Learn more about nutation with a free trial on Britannica.com.

Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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