So grammar nazi, you think you know ?. Well, you have no idea.
easily set on fire.
"the use of highly flammable materials"
As for Flamma, its latin and is a verb there. Go ask them.
Why Do Flammable and Inflammable Mean the Same Thing?
There is a fairly clear reason for why both these words carry the same meaning: the prefix in- does not always function as a negative prefix.
Sometimes (and this is one of those times) it serves as an intensifier. It’s fairly obvious how this could lead to problems.
Surprisingly, both flammable and inflammable coexisted peacefully in English for hundreds of years before anyone decided to do something about it. Inflammable is the older of the two, with recorded use as far back as 1574. Flammable begins to appear in 1655, when Margaret Cavendish described oil as being “hot burning and flammable” in her Philosophical and Physical Opinions. One of the reasons there was little confusion about these words is that flammable was used much less often than inflammable.
But in the 1920s the self appointed, eagle-eyed language nazis of the National Fire Protection Association (NFPA) realized that many people were viewing the in- in inflammable as a negative prefix, and were at risk of consequently incinerating themselves at a much higher rate than was desirable. The NFPA advocated to have flammable used exclusively for warning labels (such as are found on mattresses, oil cans, and other things that will catch on fire if you put a match to them), and managed to slightly nudge our language toward a more sensible path. Though in the recent past flammable is used more often than inflammable, this pair still incites controversy—and clueless fools would want to look ignorant.