Etymologically
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radioactive

This is the current revision of this entry, as edited by bogdan on 24 October 2026 at 18:43. This address is a permanent link to this version.
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Pronunciation

  • UK: /ˌɹeɪdiəʊˈaktɪv/[1]
  • US: /ˌɹeɪdioʊˈæktɪv/[1]

Etymology

It is formed from English radio- + active,[2][3][4][5] after French radioactif, coined by Pierre Curie and Marie Skłodowska-Curie in 1898, in a report to the French Academy of Sciences.[2][6][7] The first element is the combining form of Latin radius (“ray”),[6][2] and actif (“active”) goes back to Latin āctīvus, from āctus (“a doing”).[6] Merriam-Webster classes the word as International Scientific Vocabulary.[3]

Earliest recorded meaning

Of a substance or an atomic nucleus, tending to undergo spontaneous nuclear decay with the emission of ionizing radiation: 1898, in Nature (28 July).[2][6][3]

Semantic evolution

From 1903, in Rutherford and Soddy, the word was also used of processes and phenomena involving or produced by radioactivity.[2][6] A figurative use, of a person or place giving off intense and especially dangerous or unstable energy, is recorded from 1905.[2]

Timeline

  • 1898 – French radioactif, coined by the Curies.[2]
  • 1898 – in English, of a substance or nucleus.[2][3]
  • 1903 – of a process or phenomenon.[2][6]
  • 1905 – figurative, of a person or place giving off dangerous energy.[2]

Modern meaning

Adjective

  1. Giving off radiation through the spontaneous decay of atomic nuclei: a radioactive isotope.
  2. Of, relating to, using or caused by radioactivity: radioactive waste.
  3. (figurative) Giving off intense or dangerous energy; unstable.

Word family

  • radioactively
  • radioactivate
  • nonradioactive
  • radioactivity
  • radioactive decay
  • radioactive waste

References

  1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c d e f g h i j Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  3. ^ a b c d Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  4. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
  5. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
  6. ^ a b c d e f Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  7. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.