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 signature is a subtle imbalance in potassium isotopes, marked by a deficit of potassium-40.
—
Mrigakshi Dixit, Interesting Engineering, 14 Oct. 2025
Previous studies of lunar samples have found the ratio of different isotopes of oxygen in the moon's mantle broadly match that on Earth, suggesting the moon is formed mostly of debris from Earth.
—Keith Cooper, Space.com, 13 Oct. 2025
Some other elements in nature with no stable isotope are technetium, polonium, actinium and uranium.
—Kelling Donald, The Conversation, 13 Oct. 2025
After starting his career working in carbon dating – a process that involves tracking the decay of radioactive isotopes – the former semi-pro baseball player studied radiochemistry, which involves the use of radioactive substances in everything from power to medicine.
—Andre Mouchard, Oc Register, 10 Oct. 2025
See All Example Sentences for isotope
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Mrigakshi Dixit, Interesting Engineering, 14 Oct. 2025
Previous studies of lunar samples have found the ratio of different isotopes of oxygen in the moon's mantle broadly match that on Earth, suggesting the moon is formed mostly of debris from Earth.
—Keith Cooper, Space.com, 13 Oct. 2025
Some other elements in nature with no stable isotope are technetium, polonium, actinium and uranium.
—Kelling Donald, The Conversation, 13 Oct. 2025
After starting his career working in carbon dating – a process that involves tracking the decay of radioactive isotopes – the former semi-pro baseball player studied radiochemistry, which involves the use of radioactive substances in everything from power to medicine.
—Andre Mouchard, Oc Register, 10 Oct. 2025
See All Example Sentences for isotope
Cite this Entry
“Isotope.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/isotope. Accessed 20 Oct. 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
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