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
The scientists found that the ratio of the heavier potassium isotope, potassium-41, relative to potassium-39 is greater in the samples from the South Pole–Aitken Basin than in samples from the near side collected by the Apollo missions and lunar meteorites.
—
Keith Cooper, Space.com, 23 Jan. 2026
And outside of sheer impact threats, some of this debris includes materials, such as radioactive isotopes for nuclear reactors or volatile, toxic rocket fuel, that are very environmentally hazardous.
—Lee Billings, Scientific American, 21 Jan. 2026
Meanwhile, its nuclear facilities, which have uses ranging from fuel control to isotope separation, are being positioned by the company to help build new reactors, as the industry experiences a renaissance amid rising power demand, according to its website.
—Bloomberg, Twin Cities, 20 Jan. 2026
Chemically, the study revealed a sharp decline in carbon isotope values during this period.
—Maria Mocerino, Interesting Engineering, 18 Jan. 2026
See All Example Sentences for isotope
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Keith Cooper, Space.com, 23 Jan. 2026
And outside of sheer impact threats, some of this debris includes materials, such as radioactive isotopes for nuclear reactors or volatile, toxic rocket fuel, that are very environmentally hazardous.
—Lee Billings, Scientific American, 21 Jan. 2026
Meanwhile, its nuclear facilities, which have uses ranging from fuel control to isotope separation, are being positioned by the company to help build new reactors, as the industry experiences a renaissance amid rising power demand, according to its website.
—Bloomberg, Twin Cities, 20 Jan. 2026
Chemically, the study revealed a sharp decline in carbon isotope values during this period.
—Maria Mocerino, Interesting Engineering, 18 Jan. 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 29 Jan. 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
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