attenuation

Etymology

It is inherited from Middle English attenuacioun,^[2] borrowed from Latin attenuātiō (“a lessening”),^[3][4][5][6] a noun of action from attenuō (“to make thin, lessen, diminish”),^[3][4][5] formed from ad- (“to”) and tenuō (“to make thin”), from tenuis (“thin”),^[4] from Proto-Indo-European *ten- (“to stretch”).^[4] The Middle English Dictionary names Latin and Old French as its sources,^[2] and the Shorter Oxford allows French atténuation beside the Latin.^[7]

Earliest recorded meaning

Of persons, emaciation, and of diet, reduction: before 1425, in the Middle English translation of Chauliac.^[2][4] The OED, whose entry is not fully revised, first records the word in 1594, in Plat's Jewell House, in the sense of making less dense.^[3]

Semantic evolution

The word kept the Latin idea of making thin: the body's wasting (Middle English, and in Donne before 1631), as well as, from 1594, the thinning of a liquid or gas, especially of the wort in brewing and distilling.^[2][3][7] Johnson (1755) defined it as the making of anything thin or slender, a lessening.^[8] In the 19th century it moved from thinness to weakness: in 1868 a weakening as if by dilution, then the reduction of a disease's force or of a microorganism's virulence,^[3][7] and in electricity the decrease in the amplitude of a signal or current, recorded by 1838 in Etymonline^[4] but only from 1887, in Heaviside, in the OED.^[3] Collins now gives as its technical sense the loss of energy by radiation passing through matter.^[9]

Timeline

• c. 1425 – emaciation; reduction of diet.^[2][4]
• 1594 – making less dense; in brewing and distilling, thinning of the wort.^[3] Etymonline dates this sense to the 1590s.^[4]
• before 1631 – making thin or slender; emaciation.^[3]
• 1868 – weakening, as if by dilution; later of a disease or a microorganism.^[3]
• 1887 – the decrease in amplitude of an electrical signal or current.^[3] Etymonline dates the electrical sense to 1838.^[4]

Meanings

Noun

1. The act or process of making or becoming thinner, weaker or less, or the resulting state: the gradual attenuation of the old alliance.^[9][6]
2. (physics) The loss of energy or intensity of radiation, sound or an electrical signal as it passes through a medium.^[9][3][7]
3. (medicine) Reduction of the virulence of a pathogen.^[3][7]
4. In brewing, the reduction in the density of the wort during fermentation.^[3][7]
5. Thinning of the body; emaciation.^[6][3][7]

Related words

• attenuate
• tenuous
• thin
• extenuate

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e Kurath, Hans; Kuhn, Sherman M.; Lewis, Robert E., eds. (1952–2001), Middle English Dictionary, Ann Arbor: University of Michigan Press; online edition ed. Frances McSparran et al. (2000–2018)
3. ^ 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
4. ^ a b c d e f g h i Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
5. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
6. ^ a b c Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
7. ^ a b c d e f g Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
8. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
9. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins