Etymologically
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probability

Etymology and origin of the English word probability

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Confidence
Established
Formation
Borrowing
First attested
mid-15th century
From
Middle English probabilite
Ultimate origin
Latin (probabilitas)

Pronunciation

  • IPA: /ˌpɹɒb.əˈbɪl.ɪ.ti/ (UK); /ˌpɹɑ.bəˈbɪl.ə.ti/ (US)[1]

Etymology

It is inherited from Middle English probabilite, from Old French probabilité and directly from Latin probābilitās (“credibility, probability”),[2][3][4] from probābilis, provable, credible (see probable).[2][5]

Earliest recorded meaning

Likelihood, the appearance of truth: the mid-15th century in Etymonline, 1551 in the OED.[2][6]

Semantic evolution

Something likely to be true or happen is from the 1570s (1576).[2][6] In all probability is from before 1602.[6] The mathematical sense, the frequency with which a proposition is found true or an event occurs, measured as a ratio, is from 1718.[2][6] In the United States probabilities were weather forecasts (1875), and Old Probabilities a humorous name for the chief signal officer who issued them.[2][6]

Timeline

  • mid-15th century – likelihood.[2]
  • 1576 – a probable event.[6]
  • 1718 – mathematical probability.[6]
  • 1875 – weather probabilities (US).[6]

Modern meaning

Noun

  1. The quality of being probable; likelihood.
  2. A probable event or situation.
  3. (mathematics, statistics) A measure from 0 to 1 of how likely an event is to occur.

Word family

  • improbability
  • nonprobability
  • probabilistic
  • probit
  • conditional probability
  • joint probability
  • probability density
  • probability density function

References

  1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c d e f g Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  3. ^ 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. ^ Pearsall, Judy, ed. (1998), The New Oxford Dictionary of English, Oxford: Clarendon Press
  6. ^ a b c d e f g h Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press
Cite this entry

“Probability.” Etymologically, 17 Oct. 2026, etymologically.com/en/probability. Accessed 17 Oct. 2026.

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