delusion

Etymology

It is inherited from Middle English delusioun,^[2][3][4] borrowed from Latin dēlūsiō (“a deceiving”),^[5][6][2][7] a noun of action from dēlūsus, the past participle of dēlūdō (“to play false, mock, deceive”),^[6][2][3] from dē- and lūdō (“to play”).^[6][2] The ODE and the Shorter Oxford call the source Late Latin.^[8][9] The OED compares a rare French delusion of the 16th century.^[5] It belongs with delude, and Klein compares allusion.^[7]

Earliest recorded meaning

The act of deceiving someone with false impressions, or the state of being so deceived: about 1420, in Lydgate's Story of Thebes,^[5][4] where someone is put in dilusioun, that is, deceived.^[4] Etymonline dates it to the early 15th century.^[6]

Semantic evolution

In the 15th and 16th centuries the word meant deceit or trickery, the deluding of a person by someone else;^[6][4] the sense of cheating someone in his expectations was used until the mid-17th century.^[5] From the 1550s it was also a false impression or a fixed false belief, especially as a symptom of mental disorder.^[5][6] Johnson (1755) gave "a cheat; guile; deceit" first and "a false representation; illusion" second.^[10] The phrase delusions of grandeur is recorded from 1840,^[6] and the OED records from 1909 the sense of a false belief that one is more important than one is.^[5] In American use of the early 20th century it could also mean a fixed fondness for something.^[5]

Timeline

• c. 1420 – the deluding of someone with false impressions, in Lydgate.^[5][4]
• before 1513 – the cheating of someone in his expectations (obsolete by 1656).^[5]
• 1552 – a false impression or fixed false belief (the mental sense from the 1550s in Etymonline).^[5][6]
• 1606 – evasion (obsolete).^[5]
• 1840 – delusions of grandeur.^[6]
• 1909 – a false belief about one's own importance.^[5]

Meanings

Noun

1. A mistaken or misleading belief or idea: He was under the delusion that the job would be easy.^[11][3][5]
2. In psychiatry, a false belief held firmly against clear evidence to the contrary, as a symptom of mental disorder.^[11][3][5]
3. The act of deluding someone, or the state of being deluded.^[11][3][5]
4. delusions of grandeur: a false belief in one's own importance.^[11][6][5]

Word family

• delusional
• delusionary
• self-delusion

Related words

• delude
• delusive
• delusory
• illusion
• allusion
• elusion
• ludicrous
• prelude

Usage notes

Etymonline, after the Century Dictionary, distinguishes a delusion, a false belief that the mind has wholly accepted as true, from an illusion, a false impression from the senses or imagination that is held only provisionally.^[6] Collins likewise refers the psychiatric sense to illusion and hallucination.^[11]

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
3. ^ a b c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
4. ^ 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)
5. ^ a b c d e f g h i j k l m n o p Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
6. ^ a b c d e f g h i j k Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
7. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
8. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
9. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
10. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
11. ^ a b c d e Collins English Dictionary (2023), Glasgow: HarperCollins