Science, Tech, Math › Science Flammable Definition Share Flipboard Email Print This is the hazard symbol for flammable substances. European Chemicals Bureau Science Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry in Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate by Anne Marie Helmenstine, Ph.D. Updated March 07, 2017 Definition: Flammable is a property of a material relating how easily the material ignites or sustains a combustion reaction.Also Known As: inflammableAntonyms: nonflammableCommon Misspellings: flammible Continue Reading