flammable
adjective
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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 flammable in a Sentence
Ethan Baron, Mercury News, 7 Sep. 2025
Dead, dry leaves, grasses and branches are more flammable than living plants.
—Nan Sterman, San Diego Union-Tribune, 6 Sep. 2025
In its former life, as a printing plant, workers and machines dealt with highly flammable chemicals.
—Eileen Falkenberg-Hull, MSNBC Newsweek, 4 Sep. 2025
While doctors have significantly refined their techniques over the subsequent 150 years—ether made patients throw up and was flammable enough to cause mid-surgery explosions—there are still outstanding questions about how anesthesia works.
—Rj MacKenzie, Popular Science, 3 Sep. 2025
See All Example Sentences for flammable
Cite this Entry
“Flammable.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/flammable. Accessed 12 Sep. 2025.
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flammable
adjective
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