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
These contain enriched uranium, which is high in the fissionable isotope uranium-235.
—
David Szondy, New Atlas, 28 Dec. 2024
Uranium-238 is uranium’s most relatively abundant isotope, making up 99 percent of the naturally occurring form of the element.
—Eli Wizevich, Smithsonian Magazine, 20 Dec. 2024
No drones used in search for missing radioactive isotope
The image in the post shows a screenshot of a report filed with the U.S. Nuclear Regulatory Commission after a trace amount of the radioactive isotope germanium-68 went missing from a shipping container in early December in New Jersey.
—Joedy McCreary, USA TODAY, 19 Dec. 2024
Deuterium and tritium, isotopes of hydrogen with, respectively, one and two neutrons in their nuclei, are the preferred fuels for fusion because their nuclei can overcome the repulsive forces more easily than those of heavier atoms.
—IEEE Spectrum, 28 Oct. 2024
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.
David Szondy, New Atlas, 28 Dec. 2024
Uranium-238 is uranium’s most relatively abundant isotope, making up 99 percent of the naturally occurring form of the element.
—Eli Wizevich, Smithsonian Magazine, 20 Dec. 2024
No drones used in search for missing radioactive isotope
The image in the post shows a screenshot of a report filed with the U.S. Nuclear Regulatory Commission after a trace amount of the radioactive isotope germanium-68 went missing from a shipping container in early December in New Jersey.
—Joedy McCreary, USA TODAY, 19 Dec. 2024
Deuterium and tritium, isotopes of hydrogen with, respectively, one and two neutrons in their nuclei, are the preferred fuels for fusion because their nuclei can overcome the repulsive forces more easily than those of heavier atoms.
—IEEE Spectrum, 28 Oct. 2024
See all Example Sentences for isotope
Dictionary Entries Near isotope
Cite this Entry
“Isotope.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/isotope. Accessed 6 Jan. 2025.
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
Share