unreliable

Etymology

It is formed from English un- + reliable, with the negative prefix.^{[2][3][4][5][6]} The OED notes that unreliability is recorded slightly earlier, from 1809, also in Coleridge.^[2] Reliable, first recorded in Scotland in the 1560s, is formed from rely and -able;^[3] rely goes back to Old French relier (“to fasten; to assemble”), from Latin religō (“to fasten, bind fast”).^[3]

Earliest recorded meaning

That cannot or should not be relied on: 1810, in the notebooks of Samuel Taylor Coleridge.^[2][7] Weekley calls it a word coined by Coleridge;^[8] Etymonline gives a first record in 1835, from Fanny Kemble,^[3] and Dictionary.com dates it 1830–40.^[5]

Semantic evolution

The word has kept its single meaning, "not to be depended on".^[2][3] Like reliable itself, it was sometimes criticized in the 19th century,^[2] the objection to reliable being that it used -able in an irregular way.^[2][3] Weekley says that ignorant objections were often made to it, and that De Quincey proposed unrelyuponable as "more correct English".^[8] The Shorter Oxford also gives the senses "inconsistent, erratic".^[4]

Timeline

• 1560s – reliable, in Scotland.^[3]
• 1809 – unreliability, in Coleridge's letters.^[2]
• 1810 – unreliable, in Coleridge's notebooks.^[2][7]
• 1835 – used by Fanny Kemble, Etymonline's first record.^[3]
• mid 19th century – unreliableness.^[4]
• early 20th century – unreliably.^[4]

Meanings

Adjective

1. Not to be relied on; not trustworthy or dependable: an unreliable source, Her old van was too unreliable for long trips.^{[9][7][2][10]}
2. Not consistent; erratic.^[4]

Word family

• unreliability
• unreliably

Related words

• reliable
• rely
• reliability

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i 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 d e Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
5. ^ a b Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
6. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
7. ^ a b c Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
8. ^ a b Weekley, Ernest (1921), An Etymological Dictionary of Modern English, London: John Murray
9. ^ Collins English Dictionary (2023), Glasgow: HarperCollins
10. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt