infallible

Etymology

It is borrowed from Medieval Latin infallibilis,^{[2][3][4][5][6][7]} which the OED finds in Bede,^[2] formed from Latin in- (“not”) and Late Latin fallibilis (“liable to err”),^[3][6][7][5] from Latin fallō (“to deceive”).^[3][8][9] It is perhaps also borrowed from French infaillible, recorded in the 15th century, as the Shorter Oxford, Hoad and the Oxford Dictionary of English suggest.^{[8][10][9][2]} The Latin verb is also the source of fallible and fail.^[3]

Earliest recorded meaning

Incapable of error: before 1420, in Lydgate's Troy Book, according to Barnhart.^[4] The Middle English Dictionary quotes "the infallible iuggemente of God" from a translation of Higden of about 1425,^[11] and the OED's first record is from Caxton, before 1492.^[2] Etymonline dates the word to the early 15th century.^[3]

Semantic evolution

In Middle English it was said of judgement and reason, and also of power that could not fail and of a wall that could not be destroyed.^[11] The OED dates its use of things not liable to prove false from 1526, of what is certain to happen from Shakespeare's All's Well that Ends Well, and of what never fails in its action, like a remedy, from 1711, in Steele's Spectator.^[2] Johnson (1755) defined it as "privileged from errour; incapable of mistake", quoting Hooker.^[12] From 1870 it was used of the Pope, incapable of error when he defines doctrine,^[3][8] which gave infallibilism and infallibilist.^[3][8] A noun, an infallible person or thing, is recorded from 1816,^[2] and a verb "to make infallibly certain" only once, in 1656.^[2]

Timeline

• before 1420 – incapable of error, in Lydgate.^[4] The OED's first record is from before 1492.^[2]
• 1526 – of things, not liable to prove false.^[2]
• before 1616 – certain to happen, in Shakespeare.^[2]
• 1711 – never failing in its action.^[2]
• 1816 – noun, an infallible person or thing.^[2]
• 1870 – of the Pope, incapable of error in defining doctrine.^[3]

Meanings

Adjective

1. Incapable of making mistakes or being wrong: No referee is infallible.^[13][7][2]
2. Never failing; certain to work, and completely dependable: an infallible way to remove ink stains.^[13][7][2]
3. (Roman Catholic Church) Of the pope, incapable of error when defining doctrine on faith or morals.^[7][8]

Noun

1. A person or thing that cannot err or fail.^[13][2]

Word family

• infallibility
• infallibly
• noninfallible

Related words

• fallible
• fail
• fallacy
• false

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m n o Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g h Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
5. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
6. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
7. ^ a b c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
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. ^ a b Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
10. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
11. ^ a b 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)
12. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
13. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins