Why do the words flammable and inflammable mean the same thing?
Inflammable and flammable both mean “combustible.” Inflammable is the older by about 200 years. Flammable now has certain technical uses, particularly as a warning on vehicles carrying combustible materials, because of a belief that some might interpret the intensive prefix in- of inflammable as a negative prefix and thus think the word means “noncombustible.” Inflammable is the word more usually used in nontechnical and figurative contexts: The speaker ignited the inflammable emotions of the crowd.
Flammable and inflammable both carry the same basic definition. Anything that is flammable and inflammable can react with oxygen and combust. Back in WWII military officials named flammable objects (i.e. fuel tanks as inflammable or fire-proof). Obviously the tank is inflammable, but the fuel is flammable. Inflammable is also a term to ease up the tensity of the word flammable. Most people percieve the word flammable as anything that could easily burn and possibly blow up.
