Like flammable and inflammable.
A serious moment in cultural history occurred a few years ago, marking a significant takeover of public rhetoric by proles. I’m referring to gasoline trucks changing the warning word on the rear from INFLAMMABLE to FLAMMABLE. Widespread public education had at last produced a population which no longer recognized -in as an intensifier. The proles for whom the sign FLAMMABLE was devised will be impelled when they hear that something (like a book or a work of art) is invaluable to toss it into the trash immediately.— Paul Fussell, Class, 1983.