isomer

American  

[ahy-suh-mer] / ˈaɪ sə mər /

noun

1. Chemistry. a compound displaying isomerism with one or more other compounds.

2. Also called nuclear isomer.  Physics. a nuclide that exhibits isomerism with one or more other nuclides.

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isomer British  

/ ˌaɪsəˈmɛrɪk, ˈaɪsəmə /

noun

1. chem a compound that exhibits isomerism with one or more other compounds

2. physics a nuclide that exhibits isomerism with one or more other nuclides

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isomer Scientific  

/ ī′sə-mər /

1. Chemistry Any of two or more substances that have the same molecular formula but differ in their connectivity or spatial arrangement of atoms, or in their topology in macromolecules.

2. Physics Any of two or more nuclei with the same mass number and atomic number that have different radioactive properties and can exist in any of several energy states for a measurable period of time.

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Other Word Forms

• isomeric adjective

Etymology

Origin of isomer

First recorded in 1865–70; back formation from isomeric

Compare meaning

How does isomer compare to similar and commonly confused words? Explore the most common comparisons:

• isotope vs. isomer
• isomer vs. enantiomer

Example Sentences

The new workflow can also identify isomers, which are molecules with the same chemical formula but different atomic arrangements.

From Science Daily

In Xu and co-workers’ synthetic pathway, a UV-induced chemical reduction occurs that leads to the strikingly selective destruction of these unwanted by-products, ultimately producing only the biologically relevant isomers of the purines.

From Nature

Using mass spectrometry, researchers effectively identified glycan linkages, but in many instances failed to differentiate between sugar isomers.

From Nature

Switching the catalyst to its mirror image will therefore not switch the sign of the output in their model, and the model cannot predict which enantiomer is produced as the major isomer.

From Nature

This includes “all derivatives, extracts, cannabinoids, isomers, acids, salts, and salts of isomers, whether growing or not.”

From Salon