1
: one of two or more compounds, radicals, or ions that contain the same number of atoms of the same elements but differ in structural arrangement and properties
2
: a nuclide isomeric with one or more others
Examples of isomer in a Sentence
Recent Examples on the Web
That is the more potent of the drug’s two isomers and can be found in both street meth and prescription medications such as Desoxyn.
—
Daniel Libit, Sportico.com, 21 Jan. 2026
Should Trump pursue this scheme of conquest, the military’s training will have to be shattered and reassembled into a destructive version of itself, as if doctors were asked to take lifesaving medicines, reconstitute them as poisonous isomers, and then administer them to patients.
—Tom Nichols, The Atlantic, 19 Jan. 2026
The cyanobacterial toxin β-N-methylamino-L-alanine (BMAA), as well as its isomers 2,4-diaminobutyric acid (2,4-DAB), and N-2-aminoethylglycine (AEG), have been found to be extremely toxic to neurons.
—Maria Azzurra Volpe, MSNBC Newsweek, 3 Oct. 2025
Many of the products contain delta-8, an isomer of THC, the main psychoactive compound found in marijuana.
—arkansasonline.com, 9 July 2025
Certainly, by the time that pair had been folded into the crew, Cargill seemed like Owsley’s counterpart — an isomer, in chemical terms.
—John Semley, Rolling Stone, 19 Apr. 2025
This is possible since both Delta 8 is technically an isomer of CBD.
—Amber Smith, Discover Magazine, 3 Apr. 2024
The resulting compound includes non-natural THC isomers generated during the hydrogenation process.
—Dario Sabaghi, Forbes, 20 Feb. 2024
When mechanically strained, the bullvalene molecule shape-shifts into different forms, called isomers; this happens very fast, and the isomers have different electrical resistance, which alters electricity flow.
—IEEE Spectrum, 23 Oct. 2023
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Daniel Libit, Sportico.com, 21 Jan. 2026
Should Trump pursue this scheme of conquest, the military’s training will have to be shattered and reassembled into a destructive version of itself, as if doctors were asked to take lifesaving medicines, reconstitute them as poisonous isomers, and then administer them to patients.
—Tom Nichols, The Atlantic, 19 Jan. 2026
The cyanobacterial toxin β-N-methylamino-L-alanine (BMAA), as well as its isomers 2,4-diaminobutyric acid (2,4-DAB), and N-2-aminoethylglycine (AEG), have been found to be extremely toxic to neurons.
—Maria Azzurra Volpe, MSNBC Newsweek, 3 Oct. 2025
Many of the products contain delta-8, an isomer of THC, the main psychoactive compound found in marijuana.
—arkansasonline.com, 9 July 2025
Certainly, by the time that pair had been folded into the crew, Cargill seemed like Owsley’s counterpart — an isomer, in chemical terms.
—John Semley, Rolling Stone, 19 Apr. 2025
This is possible since both Delta 8 is technically an isomer of CBD.
—Amber Smith, Discover Magazine, 3 Apr. 2024
The resulting compound includes non-natural THC isomers generated during the hydrogenation process.
—Dario Sabaghi, Forbes, 20 Feb. 2024
When mechanically strained, the bullvalene molecule shape-shifts into different forms, called isomers; this happens very fast, and the isomers have different electrical resistance, which alters electricity flow.
—IEEE Spectrum, 23 Oct. 2023
Cite this Entry
“Isomer.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/isomer. Accessed 26 Jan. 2026.
Copy CitationKids Definition
isomer
noun
iso·mer
ˈī-sə-mər 
: one of two or more chemical compounds or groups that have the same numbers of atoms of the same elements but differ in structure
isomeric
adjective
ˌī-sə-ˈmer-ik
isomerism
noun
ī-ˈsäm-ə-ˌriz-əm
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