isotope
noun
iso·tope
ˈī-sə-ˌtōp 
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
: nuclide
Examples of isotope in a Sentence
Recent Examples on the Web
Deuterium, a stable and non-radioactive isotope of hydrogen that features a neutron in addition to the single proton in its core, is extremely abundant across the universe.
—
Victor Tangermann, Futurism, 25 Mar. 2026
The leak caught on camera Researchers discovered a visible plume of radioactive material escaping from a ventilation pipe near the reactor compartment, corroborated by elevated radionuclide levels in water samples and plutonium isotope ratios.
—Munis Raza, Interesting Engineering, 24 Mar. 2026
The moon station will require radioactive isotope power sources, and eventually a nuclear reactor, to survive long periods of shadow on the lunar south pole.
—Dan Vergano, Scientific American, 24 Mar. 2026
Chinese scientists have developed an alloy that almost reaches absolute zero, the coldest possible temperature, without using the scarce isotope, helium-3.
—Etiido Uko
march 23, New Atlas, 23 Mar. 2026
See All Example Sentences for isotope
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.
Victor Tangermann, Futurism, 25 Mar. 2026
The leak caught on camera Researchers discovered a visible plume of radioactive material escaping from a ventilation pipe near the reactor compartment, corroborated by elevated radionuclide levels in water samples and plutonium isotope ratios.
—Munis Raza, Interesting Engineering, 24 Mar. 2026
The moon station will require radioactive isotope power sources, and eventually a nuclear reactor, to survive long periods of shadow on the lunar south pole.
—Dan Vergano, Scientific American, 24 Mar. 2026
Chinese scientists have developed an alloy that almost reaches absolute zero, the coldest possible temperature, without using the scarce isotope, helium-3.
—Etiido Uko
march 23, New Atlas, 23 Mar. 2026
See All Example Sentences for isotope
Cite this Entry
“Isotope.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/isotope. Accessed 1 Apr. 2026.
Copy CitationKids Definition
isotope
noun
iso·tope
ˈī-sə-ˌtōp
: any of the forms of an element that differ in the number of neutrons in an atom
Medical Definition
isotope
noun
iso·tope
ˈī-sə-ˌtōp
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
: nuclide
Love words? Need even more definitions?
Merriam-Webster unabridged
