illusory

Etymology

It is borrowed from Late Latin illūsōrius (“mocking, ironical; deceptive”),^[2][3][4][5] which the Shorter Oxford calls ecclesiastical Latin.^[6] The OED derives it from illūsor,^[2] and Merriam-Webster from illūsus, the past participle of illūdō (“to mock, jeer at”), with the suffix -ōrius.^[3] Literally the verb means "to play with": it is formed from in- (“at, upon”) and lūdō (“to play”).^[7] Etymonline takes the adjective through French illusorie,^[7] while the OED and Johnson only compare illusoire.^[2][8]

Earliest recorded meaning

Tending to deceive by unreal prospects: the first record is in a letter of Queen Elizabeth I of 1599, quoted in Nares's Glossary.^[2] Etymonline likewise has the 1590s,^[7] and Merriam-Webster about 1631.^[3]

Semantic evolution

The OED and Etymonline gloss the Late Latin adjective as mocking or ironical,^[2][7] and Merriam-Webster adds deceptive.^[3] The sense of deceptive appearance developed in the Church Latin of the related noun illusion,^[7] and it is the only sense the OED and the Shorter Oxford record in English.^[2][6] Johnson (1755) glosses it with "deceiving; fraudulent", and his quotation speaks of a "fallacious and illusory use" of language.^[8] Beside "deceiving", the modern dictionaries give "based on illusion, unreal".^[3][9] The adverb illusorily dates from the mid 17th century, and the noun illusoriness from the early 18th.^[6]

Timeline

• 1599 – tending to deceive, of the nature of an illusion.^[2]
• mid 17th century – adverb illusorily.^[6]
• early 18th century – noun illusoriness.^[6]

Meanings

Adjective

1. Based on illusion; not real: The ceasefire brought only an illusory calm.^[9][3]
2. Producing illusion; deceptive: illusory promises of quick profit.^[9][3][6][2]

Word family

• illusorily
• illusoriness
• unillusory

Related words

• illusion
• illusionary
• illusive
• elusive
• ludicrous

Usage notes

Collins gives illusive as an equivalent, and warns that illusive is sometimes wrongly used where elusive is meant.^[9] Dictionary.com lists elusive and illusory as a pair open to confusion.^[5]

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
4. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
5. ^ a b Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
6. ^ a b c d e f Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
7. ^ a b c d e Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
8. ^ 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.
9. ^ a b c d Collins English Dictionary (2023), Glasgow: HarperCollins