idiocy

Etymology

It is formed from English idiot + -cy,^[2][3][4][5] on the model of pairs such as prophet and prophecy,^[2][3][5] or of lunatic and lunacy.^[6][4] Klein notes that the word was first spelled idiotcy and lost its t by analogy with prophecy.^[3] According to the revised OED, it is probably also in part borrowed from Medieval Latin idiotia (“the state of being of severely low mental capacity”), recorded in British sources from the 14th century,^[5] from Ancient Greek ἰδιωτεία (idiōteía, “the condition of a private person; uncouthness, lack of education”).^[5] Idiot is from Old French idiote (“an uneducated or ignorant person”), from Latin idiōta (“ordinary person, layman”), from ἰδιώτης (idiṓtēs, “private person, layman”).^[2][5] The French idiotie is recorded only from 1818.^[5]

Earliest recorded meaning

The state of being of severely low mental capacity: 1497, in a Tudor chamber book.^[5] Merriam-Webster Unabridged dates the word to 1523,^[7] Etymonline to the 1520s,^[2] and Dictionary.com to 1520–30.^[8]

Semantic evolution

The word began as a term, chiefly in law and later in psychiatry, for a natural lack of mental capacity, matching the medical sense of idiot.^[5] From 1528, in Skelton, it was also used of extremely foolish character or behaviour,^[5][9] the sense that now prevails, while the clinical use is dated and considered offensive.^[7][10][4] Johnson (1755) defined it simply as "want of understanding".^[11] In the 19th century it came to mean a single foolish act or remark (1822, in Coleridge's letters),^[5][9] and Walter Scott used it humorously as a mock title (1826).^[5] A rare sense "ignorance" is recorded only in Sylvester's translation of Du Bartas (1605).^[5][9] Other formations from idiot were tried in the late 16th century: idiotacy (1580s) and idiotry (1590s).^[2]

Timeline

• 1497 – the condition of having severely low mental capacity.^[5]
• 1528 – extreme foolishness or stupidity.^[5][9]
• 1605 – ignorance (rare, obsolete).^[5]
• 1822 – a foolish act or remark.^[5][9]
• 1826 – used humorously as a title.^[5]

Meanings

Noun

1. Extreme foolishness or stupidity: the sheer idiocy of the plan.^[7][10][5]
2. A foolish act or remark: one of the many idiocies of the committee.^[10][7][5]
3. (dated, offensive) Severe intellectual disability.^[7][10][5]

Related words

• idiot
• idiotic
• idiom
• idiosyncrasy

Usage notes

The clinical sense is now dated and considered offensive.^[7][10]

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
3. ^ a b c Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
4. ^ a b c Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
5. ^ a b c d e f g h i j k l m n o p q r s t Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
6. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
7. ^ a b c d e f Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
8. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
9. ^ a b c d e 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 c d e Collins English Dictionary (2023), Glasgow: HarperCollins
11. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.