immutable

Etymology

It is borrowed from Latin immūtābilis (“unchangeable”),^{[2][3][4][5][6]} and Etymonline and Barnhart add Old French immutable as a second source;^[7][8] the OED notes that the word was also French in the 15th and 16th centuries.^[2] The Latin adjective is formed from in- (“not”) and mūtābilis (“changeable”),^[2][7][5] the source of mutable, from mūtō (“to change”),^[7][5] which Etymonline, following Watkins, traces to Proto-Indo-European *mei- (“to change, go, move”).^[7] Modern French has immuable instead.^[7]

Earliest recorded meaning

Unchanging, unalterable, steadfast: 1412–20, in J. Lydgate's Troy Book, where Troilus is faithful, just and inmvtable of will.^[2][9] Barnhart dates the word to probably before 1422,^[8] and Etymonline to the early 15th century.^[7]

Semantic evolution

The Middle English Dictionary records it in Lydgate and in Bokenham, of the steadfast heart and of God's unchanging substance.^[9] Johnson (1755) glossed it "unchangeable; invariable; unalterable", quoting the Epistle to the Hebrews.^[6] From 1621 it was used technically of what does not vary between cases, such as markings that are the same in every member of a species.^[2][4] In 1581 the OED also records it once with the opposite meaning, "mutable", with im- as an intensive prefix; this use is obsolete.^[2]

Timeline

• 1412–20 – unchanging, unalterable, in Lydgate's Troy Book.^[2][9]
• 1581 – changeable, im- as an intensive prefix (obsolete).^[2]
• 1621 – not varying between individual cases, invariable.^[2]

Meanings

Adjective

1. Not able to change or be changed; unalterable: the immutable rules of the game.^{[3][10][11][2]}
2. (technical) Not varying from case to case; invariable.^[2][4]

Word family

• immutability
• immutably
• immutableness

Related words

• mutable
• mutation
• mutate
• commute

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
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 Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
6. ^ 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.
7. ^ a b c d e f Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
8. ^ a b Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
9. ^ a b c 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)
10. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
11. ^ Collins English Dictionary (2023), Glasgow: HarperCollins