Flammable, Inflammable, and Nonflammable

Commonly Confused Words

flammable and inflammable
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Two of these three words have the same meaning—but which two?

Definitions

The adjectives flammable and inflammable mean the same thing: easily set on fire and capable of burning quickly. Metaphorically inflammable can mean easily angered or excited.

The older word for something capable of burning is inflammable. Early in the 19th century the word flammable was coined as a synonym for inflammable. See the usage notes below.

The adjective nonflammable means not easily set on fire.

Examples

  • Approved metal safety cans should be used for the handling of flammable liquids.
  • When you are working with lasers, make sure that there are no inflammable materials in the immediate vicinity.
  • The most common nonflammable gas of all the compressed gases is oxygen.

Usage Notes

  • "For the record, 'inflammable' does mean 'burnable.' And it's meant that since at least 1605, according to the Oxford English Dictionary. 'Flammable,' the new kid on the block, didn't appear in print until more than three hundred years later.
    "The cause of all the confusion is the 'in' at the beginning of 'inflammable.' It turns out that the prefix in- can make a word negative (as in words like 'incapable,' 'inflexible,' 'incompetent'), or it can add emphasis ('invaluable,' 'inflame,' 'intense'), or it can mean 'within' ('incoming,' 'inbreeding,' 'infighting'). The in- of 'inflammable' is of the emphatic type—it's called an intensive or an intensifier. . . .
    "In the 1920s [the National Fire Protection Association] called for using 'flammable' instead of 'inflammable,' which it considered confusing because of that in- at the beginning. Insurers and other fire-safety advocates soon joined the cause. In 1959, the British Standards Institution took up the torch: 'In order to avoid any possible ambiguity, it is the Institution's policy to encourage the use of the term 'flammable' and 'non-flammable' rather than 'inflammable' and 'non-flammable.'
    "Which word should a careful writer use today? Well, history may be on the side of 'inflammable,' but common sense wins here. If you want to be sure you're understood--say, the next time you see a smoker about to light up near a gas pump—go with 'flammable.'"
    (Patricia T. O'Conner and Stewart Kellerman, Origins of the Specious: Myths and Misconceptions of the English Language. Random House, 2010)
  • Our files show that both forms continue to be used. Flammable seems to be less common in British English than it is in American English and inflammable correspondingly more common. Flammable is used literally; figurative use belongs to inflammable."
    (Merriam-Webster's Dictionary of English Usage. Merriam-Webster, 1994)
  • "The fact that even in England often the wrong meaning 'non-flammable' was ascribed to the word 'inflammable' shows that the word 'inflammable' is both an intralingual and an interlingual false friend."
    (Christoph Gutknecht, "Translation." The Handbook of Linguistics, ed. by Mark Aronoff and Janie Rees-Miller. Blackwell, 2003)
  • "Flammable, inflammable, and nonflammable. Why are there three? Don't you think that two ought to serve the purpose? I mean either the thing flams or it doesn't!"
    (George Carlin, Carlin at Carnegie, 1982)

Practice

(a) _____ or combustible liquids should not be stored in stairways or in areas used for exits.

(b) The Douglas-fir and the giant sequoia of western North America have developed thick _____ bark to insulate the living tissue from the heat of the flames.

(c) For several decades, foam has been used as the primary agent for fighting fires involving _____ liquids.

Answers to Practice Exercises: Flammable, Inflammable, and Nonflammable

(a) Flammable [or Inflammable] or combustible liquids should not be stored in stairways or in areas used for exits.

(b) The Douglas-fir and the giant sequoia of western North America have developed thick nonflammable bark to insulate the living tissue from the heat of the flames.

(c) For several decades, foam has been used as the primary agent for fighting fires involving flammable [or inflammable] liquids.