protium

P3R1O1T1I1U1M3
UK/ˈpɹəʊ.tiəm/US/ˈpɹoʊ.tiəm/

noun

The lightest and most common isotope of hydrogen, having a single proton and no neutrons: 11H. It is the only stable nuclide with no neutrons.

“This radioactive decay leaves behind a protium as well.”

Similar
mul:H-1mul:¹Hhydrogenhydrogen-1hydrogen 1light hydrogennormal hydrogen
OriginAncient Greek πρῶτος →
RareScrabble 11
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Meanings

nounprotium (plural protiums)

plural protiums

  1. natural sciencesThe lightest and most common isotope of hydrogen, having a single proton and no neutrons: 11H. It is the only stable nuclide with no neutrons.

    So far there are no differences among the protiums extracted at various labs, except for concentration levels.

    Synonyms: mul:H-1, mul:¹H, hydrogen, hydrogen-1, hydrogen 1, light hydrogen, normal hydrogen

  2. An atom of this isotope.

    This radioactive decay leaves behind a protium as well.

Synonyms & antonyms

nounThe lightest and most common isotope of hydrogen, having a single proton and no neutrons: 11H. It is the only stable nuclide with no neutrons.

Similar
mul:H-1mul:¹Hhydrogenhydrogen-1hydrogen 1light hydrogennormal hydrogen
Also see
hydrogenhydrogen-1light hydrogennormal hydrogen

Origin

  1. Ancient Greekπρῶτος“first”
  2. Englishprotium

From proto- + -ium. From Ancient Greek πρῶτος (prôtos, “first”).

More words from Ancient Greek

Full word history & related roots →

Translations

Afrikaans protium
  • protiumlightest isotope of hydrogen
Bulgarian про́тий
  • про́тий (prótij)lightest isotope of hydrogen
Catalan proti
  • protilightest isotope of hydrogen
Chinese Mandarin 氕
  • 氕 (piē)lightest isotope of hydrogen
Dutch protium
  • protiumlightest isotope of hydrogen
Esperanto procio
  • prociolightest isotope of hydrogen
Finnish protium
  • protiumlightest isotope of hydrogen
French protium
  • protiumlightest isotope of hydrogen
German Protium
  • Protiumlightest isotope of hydrogen
Hungarian prócium
  • próciumlightest isotope of hydrogen
Icelandic einvetni, prótín
  • einvetnilightest isotope of hydrogen
  • prótínlightest isotope of hydrogen
Italian prozio
  • proziolightest isotope of hydrogen
Japanese 軽水素, プロチウム
  • 軽水素 (keisuiso)lightest isotope of hydrogen
  • プロチウム (purochiumu)lightest isotope of hydrogen
Korean 프로튬
  • 프로튬 (peurotyum)lightest isotope of hydrogen
Polish prot
  • protlightest isotope of hydrogen
Portuguese prótio
  • prótiolightest isotope of hydrogen
Russian про́тий
  • про́тий (prótij)lightest isotope of hydrogen
Spanish protio
  • protiolightest isotope of hydrogen
Cite this entry
APA

protium. (n.d.). In WatkinsX Dictionary. Retrieved November 2, 2026, from https://dictionary.watkinsx.com/word/protium

MLA

“protium.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/protium. Accessed November 2, 2026.

Chicago

WatkinsX Dictionary, s.v. “protium,” accessed November 2, 2026, https://dictionary.watkinsx.com/word/protium.

Source: protium on Wiktionary, CC BY-SA 4.0.