单词 | nutation |
释义 | nutation[ noo-tey-shuhn, nyoo- ] / nuˈteɪ ʃən, nyu- / nounan act or instance of nodding one's head, especially involuntarily or spasmodically. Botany. spontaneous movements of plant parts during growth. Astronomy. the periodic oscillation observed in the precession of the earth's axis and the precession of the equinoxes. Mechanics. the variation of the inclination of the axis of a gyroscope to the vertical. Origin of nutation1605–15; <Latin nūtātiōn- (stem of nūtātiō), equivalent to nūtāt(us) (past participle of nūtāre to nod repeatedly; nū- nod + -tā- frequentative suffix + -tus past participle ending) + -iōn--ion; cf. numen OTHER WORDS FROM nutationnu·ta·tion·al, adjectiveWords nearby nutationnu soul, Nüsslein-Volhard, nut, nutant, nutate, nutation, nutbrown, nutcase, nutcracker, Nutcracker Suite, nut dash Dictionary.com UnabridgedBased on the Random House Unabridged Dictionary, © Random House, Inc. 2020 Example sentences from the Web for nutationBritish Dictionary definitions for nutationnutation / (njuːˈteɪʃən) / nounastronomy a periodic variation in the precession of the earth's axis causing the earth's poles to oscillate about their mean position physics a periodic variation in the uniform precession of the axis of any spinning body, such as a gyroscope, about the horizontal Also called: circumnutation the spiral growth of a shoot, tendril, or similar plant organ, caused by variation in the growth rate in different parts the act or an instance of nodding the head Derived forms of nutationnutational, adjectiveWord Origin for nutationC17: from Latin nutātiō, from nūtāre to nod 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 Medical definitions for nutationnutation [ nōō-tā′shən ] 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. Scientific definitions for nutationnutation [ nōō-tā′shən ] 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. 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 © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved. |
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