flammable

Etymology

It is borrowed from Latin flammō (“to set on fire”) with the suffix -able.^{[2][3][4][5][6]} The Latin verb comes from flamma (“flame, blazing fire”),^[7][3][8][9] the source of flame,^[3][5] and the American Heritage Dictionary traces the noun to Proto-Indo-European *bhel-.^[7] The older inflammable comes from French inflammable, from Medieval Latin inflammābilis, from inflammō (“to set on fire”).^[3][10]

Earliest recorded meaning

Capable of being set on fire, the same as inflammable: 1813, in Thomas Busby's translation of Lucretius.^[2][3][4] Dictionary.com dates the word to 1805–15.^[6]

Semantic evolution

The OED describes the word as revived in modern use.^[2][11] In the 20th century it came back as a way of avoiding the ambiguity of inflammable, whose prefix in- can be misread as a negative.^[3][10] Merriam-Webster describes it as the word now used in technical language instead of inflammable,^[4][12] and the Random House dictionary notes its use as a warning on vehicles carrying combustible goods.^[10] It is also used figuratively, of an issue or a relationship likely to flare up into conflict,^[4][1] and as a noun, a flammable substance.^[4][12][13]

Timeline

• 1813 – capable of being set on fire.^[2][3][4]
• 20th century – revived, chiefly in technical and warning use, in preference to inflammable.^[3][2][4]

Meanings

Adjective

1. Easily set on fire and quick to burn; combustible: Keep the paint thinner away from the stove, as it is highly flammable.^[7][4][14]
2. Figuratively, likely to cause anger or conflict: a flammable dispute over water rights.^[4][1]

Noun

1. A flammable substance.^[4][12][13]

Word family

• flammability

Related words

• inflammable
• inflammation
• inflammatory
• flame
• inflame

Usage notes

Flammable and inflammable have the same meaning when used of materials.^[14][13][10] Inflammable is the older word, by about 200 years.^[10] Because the prefix of inflammable can be taken for the negative in-, so that the word is read as "not flammable", flammable is preferred on warning labels and in other safety contexts,^[14][13][10] and since the 1980s inflammable has sometimes been discouraged in such warnings.^[3] Inflammable remains the usual word in figurative, non-technical use, as of a crowd's feelings.^[14][10]

References

1. ^ a b c Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g h i Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c d e f g h i j Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
5. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
6. ^ a b Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
7. ^ a b c The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
8. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
9. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
10. ^ a b c d e f g Random House Webster's Unabridged Dictionary (1999), 2nd ed., New York: Random House
11. ^ Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press
12. ^ a b c Gove, Philip Babcock, ed. (1961), Webster's Third New International Dictionary of the English Language, Unabridged, Springfield, Mass.: G. & C. Merriam
13. ^ a b c d The American Heritage Dictionary of the English Language (1992), 3rd ed., Boston: Houghton Mifflin
14. ^ a b c d Collins English Dictionary (2023), Glasgow: HarperCollins