acyclicadj.
/(ˌ)eɪˈsʌɪklɪk/, U.S. /eɪˈsaɪklɪk/ 1. Botany. Of parts of a flower, leaves, etc.: not arranged in circles or whorls; spirally arranged. Cf. cyclic adj. 4.
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1853 A. Henfrey tr. A. Braun Refl. on Phenomenon of Rejuvenescence in Nature in A. Henfrey Bot. & Physiol. Mem. 77 The gradual increase of length is exhibited most remarkably with an acyclic structure of the calyx.
1878 W. R. McNab Bot.: Outl. Classif. Plants viii. 179 The flowers generally have the parts in whorls (cyclic). Sometimes they are wholly (acyclic) or partially spiral (hemicyclic).
1910 New Phytologist 9 335 The flowers are noticeable for their acyclic structure,—there are numerous spirally arranged sepals, petals and stamens.
1952 P. Mann Systematics Flowering Plants iii. 262 The arrangement of the parts may continue the spiral arrangement of the leaves (acyclic); or may be in rings (cyclic).
2002 G. Theissen & K. Kaufmann in B. R. Jordan Molecular Biol. & Biotechnol. Flowering (ed. 2) vi. 140 Taxa belonging to the ANITA clade of basal angiosperms have..partially acyclic flowers.
2. Chiefly Physics. Not moving in circles; (of motion) not cyclic.
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1869 W. Thomson in Trans. Royal Soc. Edinb. 25 253 Irrotational motion may be either acyclic or cyclic.
1873 J. C. Maxwell Treat. Electr. & Magnetism I. 137 As the negative region continues to expand till it fills all space, it loses every degree of cyclosis it has acquired, and becomes at last acyclic.
1902 Encycl. Brit. XXVII. 570/2 The system now behaves, as regards the co-ordinates q1, q2..qm, exactly like the acyclic type there contemplated.
1963 New Scientist 7 Feb. 294 A commercial-scale acyclic generator has been constructed and put to work.
2007 W. P. Graebel Adv. Fluid Mech. ii. 84 There cannot be two different forms of acyclic irrotational motion.
3. Chemistry. Of a compound: not having a ring-shaped arrangement of atoms; having an open-chain structure. Cf. cyclic adj. 7.
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1890 R. A. Witthaus Med. Student's Man. Chem. (ed. 3) ii. 397 Although the members of the acyclic and of the cyclic families are not readily converted into each other, acyclic compounds are frequently grafted upon cyclic.
1913 A. G. Bloxam & S. J. Lewis Bloxam's Chem. (ed. 10) 544 There are two great divisions of organic compounds (a) The acyclic, open-chain, fatty or aliphatic..series;..(b) the cyclic or closed-chain series.
1966 Nomencl. Org. Chem. (I.U.P.A.C.) (ed. 2) A. 6 The first four saturated unbranched acyclic hydrocarbons are called methane, ethane, propane and butane.
2001 J. Clayden et al. Org. Chem. xiv. 347 Cyclic acetals..are more resistant to hydrolysis than acyclic ones and easier to make.
This entry has been updated (OED Third Edition, December 2011; most recently modified version published online December 2021).
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adj.1853