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1. The phenomenon of the existence of isomers.
2. The complex of chemical and physical phenomena characteristic of or attributable to isomers.
3. The state or condition of being an isomer.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


1. (Chemistry) the existence of two or more compounds having the same molecular formula but a different arrangement of atoms within the molecule. See also stereoisomerism, optical isomerism
2. (General Physics) the existence of two or more nuclides having the same atomic numbers and mass numbers but different energy states
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(aɪˈsɒm əˌrɪz əm)

1. the relation of two or more compounds, radicals, or ions that are composed of the same kinds and numbers of atoms but differ from each other in structural or spatial arrangement.
2. the relation of two or more nuclides that have the same atomic number and mass number but different energy levels and half-lives.
3. the state or condition of being isomerous.
i•so•mer•ic (ˌaɪ səˈmɛr ɪk) adj.
i`so•mer′i•cal•ly, adv.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.isomerism - the state of being an isomer; the complex of chemical and physical phenomena characteristic of isomers
state - the way something is with respect to its main attributes; "the current state of knowledge"; "his state of health"; "in a weak financial state"
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in periodicals archive ?
connection not included above (i.e., crisscross heart, isomerism, heterotaxy syndromes, ventricular inversion),
The most common congenital diseases associated with complete AVB include atrioventricular septal defect (isolated or associated with left atrial isomerism) and corrected congenital transposition of the great arteries.
An echocardiogram was performed, and revealed the presence of left atrial isomerism (common atrium, interrupted inferior vena cava and bilateral left atrial appendages).
According to Garrison [11], 30% of registered pesticides indicate sort of spatial isomerism. Among them, pyrethroids should be highlighted.
Li, "Nature of isomerism in exotic sulfur isotopes," Physical Review Letters, vol.
Kostic, "Effects of linkage isomerism and of acid-base equilibria on reactivity and catalytic turnover in hydrolytic cleavage of histidyl peptides coordinated to palladium(II).
Koorsen et al., "The effect of geometrical isomerism of 3,5-dicaffeoylquinic acid on its binding affinity to HIV-integrase enzyme: a molecular docking study," Evidence-Based Complementary and Alternative Medicine, vol.
Matsuhisa, "Sutureless pericardial repair of total anomalous pulmonary venous connection in patients with right atrial isomerism," Interactive Cardio Vascular and Thoracic Surgery, vol.
Wadekar, "Effect of Ring Isomerism on Spectral and Antimicrobial Studies of Sm (III) Juglonates," IOSR Journal of Applied Chemistry, vol.
Pathogenesis mutations in specific RP genes such as retinol binding and 3',5'-cyclic-GMP phosphodiesterase activity would evidently interfere with rod dysfunction or structural isomerism and give rise to congenital night blindness.
But her parents have been warned Honey-Rose may not reach adulthood as she also has atrial isomerism - abnormal atria - and pulmonary atresia, meaning the pulmonary valve did not form properly.