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Question: What Is the Difference Between Flammable and Inflammable?
Flammable and inflammable are two words that are commonly confusing. You can tell both words pertain to flames, but it's difficult to know whether they mean the same thing or are opposites.
Answer: Flammable and inflammable mean exactly the same thing... burns easily.
Why are there two different words? According to Merriam-Webster's Dictionary of English Usage, back in the 1920s the National Fire Protection Association urged people to start using the word 'flammable' instead of 'inflammable' (which is the original word) because they were concerned some people might think inflammable meant not-flammable. Actually, the in- in inflammable was derived from the Latin preposition meaning en- (like enflamed), not the Latin prefix meaning -un. It's not like everyone knew the derivation of the word, so the change probably made sense. However, confusion persists today regarding which word to use.