Etymologically
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humidity

This is the current revision of this entry, as edited by bogdan on 22 October 2026 at 21:07. This address is a permanent link to this version.
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Pronunciation

  • UK: /hjuːˈmɪd.ə.ti/, /hjuːˈmɪd.ɪ.ti/[1]
  • US: /hjuˈmɪd.ə.ti/[1]

Etymology

It is inherited from Middle English humidite, borrowed from Old French humidité (“dampness”),[2][3][4] from Latin hūmiditās (“moisture”),[3][5] from hūmidus (“moist, wet”).[2][3] The AHD calls the Latin noun Medieval Latin, and Merriam-Webster Late Latin;[2][6] the Oxford Dictionary of English allows a borrowing from either French or Latin.[7] In Anglo-Norman the noun was recorded in the early 13th century as one of the four qualities associated with the humours.[8]

Earliest recorded meaning

In the plural, the humours and juices of animals and plants, about 1400, in Lanfranc's Cirurgie.[4]

Semantic evolution

Lydgate used it in 1412–20 for moisture itself, the fluid that makes something damp,[4][9] and by about 1450 it meant the quality or condition of being damp.[4][9] Johnson (1755) defined it as the power of wetting other bodies.[10] The modern meteorological sense, a measure of the moisture in the air compared with the amount that would saturate it, dates from 1820; the full phrase relative humidity is recorded by 1819.[3] Meteorologists also speak of absolute humidity, the mass of water vapour in a given volume of air.[11][12]

Timeline

  • c. 1400 – plural, humours and juices of animals and plants.[4]
  • 1412–20 – moisture, damp (Lydgate).[4]
  • c. 1450 – the condition of being damp.[4]
  • 1755 – Johnson defines it as the power of wetting other bodies.[10]
  • 1819 – relative humidity.[3]
  • 1820 – a measure of moisture in the air.[3]

Modern meaning

Noun

  1. Dampness, especially of the air.
  2. The amount of water vapour in the air; relative humidity.

Word family

  • absolute humidity
  • relative humidity
  • specific humidity
  • humid
  • humidifier
  • humidify

References

  1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
  3. ^ a b c d e f Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  4. ^ a b c d e f g Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  5. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
  6. ^ Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  7. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
  8. ^ Anglo-Norman Dictionary (AND2), Aberystwyth University, anglo-norman.net (2nd ed., 2005–)
  9. ^ a b Kay, Christian; Roberts, Jane; Samuels, Michael; Wotherspoon, Irené, eds. (2009), Historical Thesaurus of the Oxford English Dictionary, Oxford: Oxford University Press; online edition (2024)
  10. ^ a b Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
  11. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
  12. ^ Collins English Dictionary (2023), Glasgow: HarperCollins