isotope

noun

iso·​tope ˈī-sə-ˌtōp How to pronounce isotope (audio)
1
: any of two or more species of atoms of a chemical element with the same atomic number and nearly identical chemical behavior but with differing atomic mass or mass number and different physical properties
2
isotopic adjective

Examples of isotope in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Each ball contained about 1/50th of a gram of radioactive isotopes, enough to register on handheld detectors but (theoretically) not enough to be harmful. Christopher McFadden, Interesting Engineering, 28 Oct. 2025 In Leipzig, Heisenberg began theoretical work on the construction of a nuclear reactor required to separate isotopes of uranium and release uranium-235. Literary Hub, 23 Oct. 2025 However, more direct measures of diet – such as stable isotopes or dental microwear – were often lacking. Aditya Reddy Kurre, The Conversation, 21 Oct. 2025 To detect such a minute signal, the researchers dissolved the powdered rocks in acid, isolated the resulting potassium, and then used an ultra-sensitive mass spectrometer to precisely measure the ratios of the element's three isotopes, according to the new study. Sharmila Kuthunur, Space.com, 20 Oct. 2025 See All Example Sentences for isotope

Word History

Etymology

is- + Greek topos place

First Known Use

1913, in the meaning defined at sense 1

Time Traveler
The first known use of isotope was in 1913

Browse Nearby Words

Cite this Entry

“Isotope.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/isotope. Accessed 30 Oct. 2025.

Kids Definition

isotope

noun
iso·​tope ˈī-sə-ˌtōp How to pronounce isotope (audio)
: any of the forms of an element that differ in the number of neutrons in an atom
isotopic adjective
isotopically adverb

Medical Definition

isotope

noun
iso·​tope ˈī-sə-ˌtōp How to pronounce isotope (audio)
1
: any of two or more species of atoms of a chemical element with the same atomic number and position in the periodic table and nearly identical chemical behavior but with differing atomic mass or mass number and different physical properties
2
isotopic adjective
isotopically adverb
isotopy noun
plural isotopies

More from Merriam-Webster on isotope

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