combustible

Etymology

It is borrowed from French combustible,^[2][3][4][5] or directly borrowed from Late Latin combūstibilis,^[3][6] from combūstus (“burnt up”), the past participle of combūrō (“to burn up, consume”).^[3][4][5] The Shorter Oxford allows Medieval Latin combustibilis as the source,^[7] and Merriam-Webster Unabridged takes the word as Middle French, formed from combustion and -ible.^[8][9] According to Etymonline, the Latin verb arose from a faulty division of ambūrō (“to burn around”), properly ambi- and ūrō (“to burn, singe”), with com- (here perhaps intensive) taking the place of the first part;^[3][10] it traces the simple verb to Proto-Indo-European *heus- (“to burn”), the root of ember.^[3] The negative incombustible and the noun combustibility are both recorded earlier, from 1471.^[2][7]

Earliest recorded meaning

Capable of being burnt, fit for burning: 1529, in T. More's Dialogue on heresies.^[2][8] Etymonline dates the word to the 1520s, and Dictionary.com to 1520–30.^[3][6]

Semantic evolution

The figurative sense, easily kindled to anger or passion, followed in the 17th century: Etymonline dates it to the 1640s and the 1989 edition of the OED to 1647,^[3][11] while the current OED's first quotation is from 1698.^[2] It belongs to a wider pattern of describing excitement in terms of heat, which Mapping Metaphor traces to the late 14th century.^[12] A sense "burning, fiery" is recorded only in 1632.^[2] As a noun, a substance that will burn, the word appears in 1688,^[2] in the 1680s in Etymonline,^[3] and figuratively from 1813.^[2] Johnson (1755) defined the adjective as "having the quality of catching fire; susceptible of fire", quoting Brown's Vulgar Errours.^[13]

Timeline

• 1529 – capable of being burnt.^[2][8]
• 1632 – burning, fiery (now obsolete).^[2]
• 1647 – figurative, easily excited to violence or passion.^[11] The current OED's first quotation is from 1698.^[2]
• 1688 – noun, a combustible substance.^[2][3]
• 1813 – noun, figurative.^[2]

Meanings

Adjective

1. Able to catch fire and burn; flammable: Keep the paint thinner away from the stove, as it is highly combustible.^[14][8][2]
2. Easily excited or angered; volatile: a combustible crowd.^[14][15][2]

Noun

1. A substance that burns readily.^[14][8][2]

Word family

• combustibility
• combustibly
• incombustible
• noncombustible
• uncombustible

Related words

• combust
• combustion
• combustor

Usage notes

In Irish English of the 19th century the adjective could mean snug, warm and comfortable;^[16] Wright quotes Kennedy's stories of County Wexford (1867, 1870).^[16] In Maine a combustible was a gale approaching hurricane force (1975), probably by association with combustion in the sense of violent agitation.^[17]

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 i Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
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 Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
8. ^ a b c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
9. ^ Gove, Philip Babcock, ed. (1961), Webster's Third New International Dictionary of the English Language, Unabridged, Springfield, Mass.: G. & C. Merriam
10. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
11. ^ a b Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press
12. ^ Mapping Metaphor with the Historical Thesaurus, University of Glasgow, mappingmetaphor.arts.gla.ac.uk
13. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
14. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins
15. ^ Merriam-Webster's Collegiate Dictionary (2003), 11th ed., Springfield, Mass.: Merriam-Webster
16. ^ a b Wright, Joseph, ed. (1898–1905), The English Dialect Dictionary, 6 vols., Oxford: Henry Frowde; via EDD Online 4.0, University of Innsbruck (CC BY 4.0)
17. ^ Cassidy, Frederic G. & Joan Houston Hall (eds.) (1985–2002), Dictionary of American Regional English, vols I–IV, Cambridge, Mass.: Belknap Press of Harvard University Press