in·​flam·​ma·​ble in-ˈfla-mə-bəl How to pronounce inflammable (audio)
: easily inflamed, excited, or angered : irascible
inflammability noun
inflammable noun
inflammableness noun
inflammably adverb

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Why Inflammable Is Not the Opposite of Flammable

Combustible and incombustible are opposites but flammable and inflammable are synonyms. Why? The in- of incombustible is a common prefix meaning "not," but the in- of inflammable is a different prefix. Inflammable comes from Latin inflammare ("to inflame"), itself from in- (here meaning "in" or "into") plus flammare ("to flame"). Flammable also comes from flammare. In the early 20th century, firefighters worried that people might think inflammable meant "not able to catch fire," so they adopted flammable and nonflammable as official safety labels and encouraged their use to prevent confusion. In general use, flammable is now the preferred term for describing things that can catch fire, but inflammable is still occasionally used with that meaning as well.

Examples of inflammable in a Sentence

some pajamas are made of inflammable material, so be careful
Recent Examples on the Web Heat also stresses old electrical systems — insulation breaks down; lubricants in relays dry out — and a not-insignificant amount of the subway’s electrical wiring dates to the 1920s and 1930s, some of it cloth-covered, inflammable, and pervious to water. Curbed, 28 July 2023 Initial checks showed the fire, which mostly affected a wing for critically ill patients, was caused by inflammable painting material at a ward under renovation, the officials said. Reuters, NBC News, 19 Apr. 2023 At the crime scene in Madison, authorities found jars with pieces of clothing, inflammable liquid and burn marks. Andrew Jeong, Washington Post, 29 Mar. 2023 The bag was filled with inflammable gas. San Diego Union-Tribune, 21 Feb. 2023 Garg said the fire started on the first floor of the building on Friday evening and spread quickly to other areas where inflammable plastic material used to manufacture equipment including security cameras and a large quantity of cardboard used for packaging were stored. Fox News, 14 May 2022 To build the next generation of better-shielded, lightweight spacecraft, engineers will have to figure out how to safely enclose the shielding material inside something airtight and inflammable. Korey Haynes, Discover Magazine, 6 June 2019 On the other hand, the batteries are sensitive to high temperatures and inherently inflammable. Yiwen Lu, Washington Post, 27 June 2022 The mighty sequoia, protected by thick bark and with its foliage typically high above the flames, was once considered nearly inflammable. Brian Melley, Anchorage Daily News, 23 July 2022 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'inflammable.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


French, from Medieval Latin inflammabilis, from Latin inflammare

First Known Use

1605, in the meaning defined at sense 1

Time Traveler
The first known use of inflammable was in 1605


Dictionary Entries Near inflammable

Cite this Entry

“Inflammable.” Dictionary, Merriam-Webster, Accessed 24 Sep. 2023.

Kids Definition


in·​flam·​ma·​ble in-ˈflam-ə-bəl How to pronounce inflammable (audio)
: easily inflamed : excitable
inflammability noun
inflammably adverb

More from Merriam-Webster on inflammable

Last Updated: - Updated example sentences
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