[ ahy-som-uh-riz-uh m ]
/ aɪˈsɒm əˌrɪz əm /


Chemistry. 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 arrangement (structural isomerism), as CH3OCH3 and CH3CH2OH, or in the arrangement of their atoms in space and therefore in one or more properties.Compare optical isomerism, stereoisomerism.
Also called nuclear isomerism. Physics. the relation of two or more nuclides that have the same atomic number and mass number but different energy levels and half-lives.
Chemistry, Physics. the phenomenon characterized by such a relation.
the state or condition of being isomerous.


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Origin of isomerism

First recorded in 1830–40; isomer(ic) + -ism Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for isomerism

British Dictionary definitions for isomerism

/ (aɪˈsɒməˌrɪzəm) /


the existence of two or more compounds having the same molecular formula but a different arrangement of atoms within the moleculeSee also stereoisomerism, optical isomerism
the existence of two or more nuclides having the same atomic numbers and mass numbers but different energy states
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 isomerism

[ ī-sŏmə-rĭz′əm ]


The phenomenon of the existence of isomers.
The complex of chemical and physical phenomena characteristic of or attributable to isomers.
The state or condition of being an isomer.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.