inconsistency

Etymology

It is formed from English inconsistent + -ency, on the pattern of consistency,^[2][3][4] or, as Etymonline, Merriam-Webster and Dictionary.com analyse it, in- (“not”) added to that noun.^[5][6][7] That noun comes from Medieval Latin consistentia or Latin cōnsistēns, the present participle of cōnsistō (“to stand firm”).^[5]

Earliest recorded meaning

Something that is inconsistent; a discrepancy: 1647, in Henry More's Philosophicall Poems.^[2] Merriam-Webster dates the word to 1643, and Etymonline to the 1640s.^[6][5]

Semantic evolution

The concrete sense, an inconsistent thing, came first, and the abstract quality of being inconsistent followed in the 1650s.^[5][2] From 1665 the word was used of people whose principles and actions disagree,^[2] and Johnson's Rambler (1750) is the first record of an inconsistent act.^[2] Johnson's dictionary (1755) defined it as such opposition that one proposition implies the denial of the other.^[8] In logic it has been a technical term since 1864.^[2]

Timeline

• 1647 – something inconsistent, a discrepancy.^[2]
• 1651 – lack of agreement between two things or parts.^[2]
• 1665 – of people, inconsistency in thought or action.^[2]
• 1750 – an inconsistent act.^[2]
• 1864 – in logic.^[2]

Meanings

Noun

1. Lack of agreement or compatibility between things: There is an inconsistency between his words and his actions.^[9][6][2]
2. Lack of steadiness or uniformity: the team's inconsistency this season.^[6]
3. Something that is inconsistent; a discrepancy: The auditors found several inconsistencies in the accounts.^[9][6][2]
4. In logic, the property of propositions that cannot all be true, or a self-contradictory proposition.^[9][2]

Related words

• consistency
• inconsistent
• consist
• consistent

Usage notes

The older form inconsistence, from the 1630s, is now rare.^[5][6]

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 Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
4. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
5. ^ a b c d e Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
6. ^ a b c d e f Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
7. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
8. ^ 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 Collins English Dictionary (2023), Glasgow: HarperCollins