rotationaladj.
/rə(ʊ)ˈteɪʃn̩(ə)l/, /rə(ʊ)ˈteɪʃən(ə)l/, U.S. /roʊˈteɪʃ(ə)n(ə)l/ I. Senses relating to alternation.
1. Agriculture.
a. Relating to or involving the rotation of crops. Cf. rotation n. 4a.
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the world > food and drink > farming > cultivation or tillage > cultivation of plants or crops > [adjective] > rotation of crops
rotational1771
four-course1846
1771 M. Peters Winter Riches i. 3 This part of winter riches may be one of the rotational changes for the culture of wheat, or barley.
1886 Ann. Rep. Mass. Board of Agric. 1885 128 A system of raising farm crops can only then be called a rotational one..when it tends to secure the production of the largest amount of valuable vegetable matter at the lowest possible cost.
1948 G. D. H. Bell Cultivated Plants Farm iv. 22 Revolutionary changes in rotational practice followed the introduction of roots and red clover to this country in the eighteenth century.
2005 Arable Crop Sector (OECD) 75 In the United States, rotational cropping of arable crops is predominant with soybeans and maize.
b. Designating a system of grazing in which animals are grazed successively on different areas of land; relating to such a system.
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the world > food and drink > farming > farm > farmland > management of pasture > [adjective]
rotational1920
1908 R. H. Elliot Clifton Park Syst. Farming 175 Dr. Shirra Gibb says: ‘I have obtained excellent results from what I term “rotation grazing”—alternating breeding sheep, feeding sheep and cattle—either yearly, or..quarterly.’]
1920 Jrnl. Ecol. 8 155 The author describes methods of avoiding the bad effects of over-grazing by rotational and deferred grazing.
1967 C. D. Blake et al. Fund. Mod. Agric. ix. 208/1 Rotational grazing is any system of handling animals which involves holding them for short periods on small sections of the total area of an available pasture and then regularly moving them..to other sections.
1987 Jrnl. Range Managem. 40 307/1 Infiltration [by water] was significantly greater under continuous grazing than under rotational deferment.
2006 G. H. Holthaus From Farm to Table iii. 49 The pastures were getting depleted and nobody understood rotational grazing.
2. Acting, arising, or performed in rotation.
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1780 J. Green Plan for Better Regulation Mariners 19 By the militia act, every landman is obliged to take a rotational chance for the defence of the state.
1796 W. Taplin Compend. Pract. & Exper. Farriery 248 At the expiration of three weeks the horse was returned, took his rotational work in the carriage, and has continued ever since perfectly sound.
1805 Sporting Mag. Feb. 236/1 The almost unprecedented variations in the weather..has so deranged our usual regularity in the recital, that we are under the necessity of deviating..from the correct rotational order in which they were originally intended.
1842 in Promethean June 69/2 A rotational council of seniors.
1852 A. De Morgan Let. 27 July in R. P. Graves Life Sir W. R. Hamilton (1889) III. 394 Members to go out by rotation each year... The rotational electors to be distributed through the year.
1964 Brit. Med. Jrnl. 15 Aug. p. xxxviii/4 (advt.) This is a rotational post between the Department of Radiotherapy at the Middlesex Hospital and the Department of Radiotherapy at Mount Vernon Hospital, Northwood.
1994 Forum Mag. (Markham, Ont.) June 7/3 In April 1993 Canada..[began] its rotational year in command of the multinational naval squadron.
II. Senses relating to turning.
3. Of the nature of rotation or turning; involving or relating to rotation. rare before late 19th cent.
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the world > time > change > alternation > rotation > [adjective]
rotary1758
rotatory1766
rotative1771
rotational1788
rotating1854
the world > movement > motion in specific manner > revolution or rotation > [adjective]
rotatory1578
dinetical1646
vertiginous1663
dinetic1668
rotary1704
rotal1724
revolutionary1734
circumrotatory1744
rotative1747
rotatorial1755
verticillary1758
circumvolutionary1809
evolutionary1828
rotational1870
circumductory1872
1788 E. Roberts Beauties of Rousseau I. 15 Descartes..could not give the first motion to these dice, nor play off the centrifugal force, but by the assistance of a rotational movement.
1870 R. A. Proctor Other Worlds than Ours v. 111 The energies indicated by mere velocity of motion, whether orbital or rotational, must be equally disregarded.
1894 E. A. Minchin tr. O. Bütschli Investig. Microsc. Foams 122 The so-called rotational streaming of the protoplasm.
1934 A. H. R. Goldie Abercromby's Weather (rev. ed.) xvi. 258 A tropical revolving storm, where the rotational speed..is high.
1937 S. L. Green Hydro- & Aero-dynamics ii. 14 There is an essential difference between motions with and without spin, i.e. between rotational and irrotational motion.
2005 M. Bjornerud Reading Rocks iii. 68 The gravitational interaction of the Sun and Moon with Earth's rotational bulge causes the Earth to precess, or wobble.
4. Physics. Of or relating to the energy possessed by an atom or molecule by virtue of its rotation; designating such energy (now recognized as quantized: cf. rotational quantum number n. at Compounds).
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the world > matter > physics > atomic physics > [adjective] > of property: resulting from rotation
rotational1894
the world > matter > physics > quantum theory > electron spin > [adjective] > possessed by virtue of rotation
rotational1894
1894 Proc. Royal Soc. 185 771 The rotational strain of each molecule will be self-contained, in the sense that the lines of twist proceeding from one atom will end on some other atom of the same molecule.
1914 Chem. Abstr. 8 859 According to the quantum hypothesis the rotational energy of a mol[ecule] varies discontinuously.
1950 W. J. Moore Physical Chem. xi. 327 A set of closely packed rotational levels is associated with each of these vibrational levels.
1973 C. Sagan Cosmic Connection (1974) iv. 27 Molecules undergo rotational transitions, due to the free rotation of the molecule.
2004 K. Nakamura & T. Harayama Quantum Chaos & Quantum Dots vi. 79 The rotational component of the orbital motion generates a loop current.
Compounds
rotational latency n. Computing a delay in accessing data on a disk arising from the time taken for the area of the disk containing the data to rotate to the position of the read-write head; cf. seek-time n. at seek n. 2.
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1962 Communications ACM 5 543/2 A sorting technique is discussed which minimizes head movement and rotational latency for a disc file Computer System.
1989 InfoWorld 13 Nov. 512/4 Once the peripheral cards become fast enough, performance is limited by factors such as disk rotational latency.
2005 Maximum PC Apr. 80/2 Access times were 1 millisecond slower than spec (9ms after subtracting rotational latency).
rotational quantum number n. Physics the quantum number J (see J n. 6c).
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1921 Proc. Royal Soc. A. 99 141 The electron..can take up an infinite number of stable orbits characterised by the rotational quantum-number n, and the radial quantum number n′.
1969 Science 10 Oct. 226/2 WJ, the equivalent width of the line with rotational quantum number J.
2008 J. W. Jewett & R. A. Serway Physics for Scientists & Engineers with Mod. Physics (ed. 7) xliii. 1266 When a molecule absorbs a photon with the appropriate energy..the rotational quantum number J either increases or decreases by one unit.
rotational symmetry n. symmetry with respect to rotation about a point (for a plane figure) or about an axis (for a three-dimensional entity).
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1907 Nature 21 Feb. 406/1 Classes [of crystals] with the same rotational symmetry round the axis.
1940 Amer. Jrnl. Psychol. 53 59 An example of..a change where rotational symmetry about a point is produced.
2005 M. Livio Equation that couldn't be Solved i. 10 Starfish have fivefold rotational symmetry; they can be rotated by 72, 144, 216, 288, and 360 degrees with no discernable difference.
This entry has been updated (OED Third Edition, November 2010; most recently modified version published online March 2022).
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adj.1771