English language strikes again with its redundant terminology. The lexicographer who decided "flammable" and "inflammable" should mean the exact same thing probably sits in their office cackling while watching chemistry students set things on fire trying to figure out which one burns. For the record, both terms indicate something can catch fire easily - the "in-" prefix doesn't negate like in "invisible," it intensifies like in "infamous." Linguistic chaos at its finest.
Linguistic Arson

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