pro·​ti·​um ˈprō-tē-əm How to pronounce protium (audio)
: the ordinary light hydrogen isotope of atomic mass 1

Examples of protium in a Sentence

Recent Examples on the Web The fuel sources are far better than protium, but the extra neutrons are sprayed around and can cause problems. Caroline Delbert, Popular Mechanics, 16 Feb. 2022

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'protium.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


New Latin, from Greek prōtos first

First Known Use

1933, in the meaning defined above

Time Traveler
The first known use of protium was in 1933

Dictionary Entries Near protium

Cite this Entry

“Protium.” Dictionary, Merriam-Webster, Accessed 2 Oct. 2023.

Medical Definition


pro·​ti·​um ˈprōt-ē-əm How to pronounce protium (audio) ˈprō-shē- How to pronounce protium (audio)
: the ordinary light hydrogen isotope of atomic mass 1

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