Etymologically
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plutonium

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Pronunciation

  • /pluːˈtoʊniəm/[1]

Etymology

It is formed from English Pluto + -ium,[2][3][4][5] with the connective -n- of Plutonian;[2] Barnhart and Merriam-Webster call it New Latin.[4][5] The dwarf planet Pluto is named after the god, Latin Plūtō, from Ancient Greek Πλούτων (Ploútōn), a name of the god of the underworld as the god of wealth,[4][3] from πλοῦτος (ploûtos, “wealth”),[4][3][6] which Etymonline traces to Proto-Indo-European *pleu- (“to flow”).[3] The name was first given by E. D. Clarke to barium in 1816, alluding to Cicero's account of the ancient temple of Pluto called the Plutonium.[2][3] For the radioactive element it was coined in 1942 by Glenn T. Seaborg and Arthur C. Wahl,[2][7][4] because the element follows neptunium in the periodic table as Pluto follows Neptune in the solar system;[3][4][6][8] the OED says it was formed after uranium and neptunium, the elements next to it.[2]

Earliest recorded meaning

Clarke's name for the element barium: 1816, in a letter of Faraday, who probably had it from his correspondence with Clarke that month.[2][9] The element sense dates from 1942, in a report by Seaborg and Wahl.[2][3][4][5]

Semantic evolution

The barium sense did not last beyond 1817,[2] although Etymonline notes it was sometimes used in the early 19th century.[3] The element was discovered in 1940 according to Barnhart, and at the University of California, Berkeley, in 1941 according to Etymonline;[4][3] the OED describes it as first produced artificially from uranium in nuclear reactors.[2] Its most stable isotope, plutonium-239, is used as a fuel in nuclear power stations and in nuclear weapons.[8][10]

Timeline

  • 1816 – Clarke's name for barium (obsolete by 1817).[2]
  • 1942 – the radioactive element of atomic number 94.[2][3][4][5]

Meanings

Noun

  1. A dense, silvery, radioactive metallic chemical element of the actinide series, atomic number 94, symbol Pu, made from uranium in nuclear reactors and used as reactor fuel and in nuclear weapons.[8][10][5][2]
  2. (obsolete, 1816–17) A name for barium.[2][9]
  • Pluto
  • pluton
  • Plutonian
  • plutonic
  • plutonism
  • plutocracy
  • neptunium
  • uranium

Usage notes

The OED and the Shorter Oxford also record an older plutonium (1613, in Purchas), a place giving off noxious or poisonous vapours, from Latin Plūtōnium and Ancient Greek Πλουτώνιον (Ploutṓnion), a noun use of the Greek adjective meaning "belonging to Pluto".[2][9]

References

  1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c d e f g h i j k l m n Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  3. ^ a b c d e f g h i j Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  4. ^ a b c d e f g h i Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
  5. ^ a b c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  6. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
  7. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
  8. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins
  9. ^ a b c Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
  10. ^ a b Soanes, Catherine; Stevenson, Angus, eds. (2004), Concise Oxford English Dictionary, 11th ed., Oxford: Oxford University Press