My understanding is that "flammable" is a revisionist word (is that called a back-construction?) decided upon precisely because it was felt "inflammable" was likely to be misunderstood as meaning fireproof.

I assure you, Giok, that despite the abovementioned concern, I have never seen "inflammable" used to mean "fireproof" -- which of course doesn't mean it could not happen, only that in my fifty-odd years, I've never seen it (and in my position as a technical editor, I might reasonably expect to see it if it was there to be seen).

Claire