Etymologically
Log in

diffuse

This is the current revision of this entry, as edited by bogdan on 1 November 2026 at 00:06. This address is a permanent link to this version.
Changes in this edit History

Pronunciation

  • UK: /dɪˈfjuːz/[1]
  • US: /dɪˈfjuz/[1]

Etymology

It is borrowed from Latin diffūsus (“spread out, extensive”), the past participle of diffundō (“to pour out, spread, scatter”),[2][3][4][5] which is formed from dis- (“apart, in every direction”) and fundō (“to pour”),[3][4][6] from Proto-Indo-European *gheu- (“to pour”).[6] The adjective may also have come through Anglo-Norman diffus or Middle French diffus;[6][7][8][9] the OED compares the French adjective, recorded in Old French from 1314, but takes the English one from Latin.[2] The Anglo-Norman adjective is recorded from about 1270, meaning spread out or rambling.[10] The verb was formed on the Latin past participial stem diffūs-, partly also by conversion of the adjective,[2][8][11] and Merriam-Webster allows Middle French diffuser as a source too;[12] the OED dates the French verb to the beginning of the 15th century.[2] Klein and Skeat refer the Latin verb to fuse, to melt.[5][13]

Earliest recorded meaning

The verb, to spread something abstract widely: before 1425, in the Northern Pauline Epistles.[2] The adjective, in the sense "confused, obscure, hard to understand", follows in 1430, in the proceedings of the Privy Council;[2] Barnhart dates it to 1413,[14][4] and Etymonline to the early 15th century.[3] Etymonline dates the verb only to the 1520s.[3]

Semantic evolution

The first sense of the adjective, confused or obscure, died out by the early 17th century according to the Shorter Oxford,[8] though the OED has it until 1817;[2] Shakespeare used the verb once, in King Lear (1608), for "to make confused".[2] The concrete sense, spread over a wide area or scattered, is recorded from about 1475,[2][4][3] and the medical use, of a disease not confined to one part of the body, from 1585.[2] Used of style, the adjective came to mean wordy or long-winded (1612 in the OED, earlier in Etymonline and the Shorter Oxford),[2][3][8] and Johnson (1755) gave the two senses "scattered; widely spread" and "copious; not concise".[15] Hoad notes that in the 18th century it became the opposite of confined and condensed.[7] Later uses were technical: in botany of a loose, open panicle (1751), of light spread evenly and softened (1794), and in phonetics (1952).[2] The verb meant to spread knowledge or ideas from before 1425, to send out light or sound in all directions from before 1475; from 1587 it also meant to scatter one's attention so as to weaken it;[2] in physics and chemistry it was used for substances intermingling by diffusion from 1801, and intransitively from 1833.[2]

Timeline

  • before 1425 – verb, to spread something abstract among many people.[2]
  • 1430 – adjective, confused, obscure, hard to understand (obsolete).[2]
  • c. 1475 – adjective, spread over a wide area; scattered.[2][4]
  • 1541 – verb, to pour down or shower over something.[2]
  • 1585 – adjective, in medicine, not confined to one part of the body.[2]
  • 1608 – verb, to make confused, in Shakespeare's King Lear.[2]
  • 1612 – adjective, of style, wordy or verbose.[2]
  • 1655 – verb, intransitive, to spread widely.[2] Etymonline dates this use to the 1650s.[3]
  • 1794 – adjective, of light, spread evenly and softened.[2]
  • 1801 – verb, in physics and chemistry, to intermingle by diffusion.[2]

Meanings

Adjective

  1. Spread out over a wide area; not concentrated: a diffuse network of small villages.[16][12][2]
  2. Using more words than needed; wordy or verbose: The report was too diffuse to hold the board's attention.[16][12][2]
  3. (medicine) Not localized; affecting a wide area of the body.[12][2]
  4. Of light, spread evenly so that it is soft and not harsh.[16][2]
  5. (botany) Spreading loosely or openly.[16][12][2]
  6. (obsolete, 1430–1817) Confused, obscure or hard to understand.[2][12][8]

Verb

  1. To spread widely, or make widely known; to disseminate: The new methods diffused slowly through the profession.[16][12][2]
  2. To send out or scatter in all directions, as light or heat.[16][2]
  3. (physics, chemistry) To intermingle, or cause to intermingle, by diffusion.[16][2]
  4. To spread thin, so as to weaken: He diffused his energy over too many projects.[2][16]

Word family

  • diffusely
  • diffuseness
  • diffusible
  • diffusate
  • interdiffuse
  • nondiffuse
  • overdiffuse
  • rediffuse

Usage notes

The adjective ends in /s/ and the verb in /z/.[2][16]

References

  1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z 27 28 29 30 31 32 33 34 35 Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  3. ^ a b c d e f g Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  4. ^ a b c d e Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
  5. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
  6. ^ a b c The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
  7. ^ a b Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
  8. ^ a b c d e Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
  9. ^ Weekley, Ernest (1921), An Etymological Dictionary of Modern English, London: John Murray
  10. ^ Anglo-Norman Dictionary (AND2), Aberystwyth University, anglo-norman.net (2nd ed., 2005–)
  11. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
  12. ^ a b c d e f g Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  13. ^ Skeat, Walter W. (1911), A Concise Etymological Dictionary of the English Language, new ed., Oxford: Clarendon Press
  14. ^ Barnhart, Robert K., ed. (1995), The Barnhart Concise Dictionary of Etymology, New York: HarperCollins
  15. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
  16. ^ a b c d e f g h i Collins English Dictionary (2023), Glasgow: HarperCollins