Did you notice that the im- prefix of impassion and impassioned are intensive while the im- prefix used with the previous word (impassionate) has the meaning of “no, not, lacking,” etc.? It shows that one cannot depend on these prefixes to mean the same thing for all words.
Not too many years ago, just about every gasoline truck in the U.S. had large signs painted on them that said, INFLAMMABLE. Since most people thought that the prefix in- meant “not”, they interpreted INFLAMMABLE to mean NOT FLAMMABLE. Now the trucks carry the painted signs: FLAMMABLE to eliminate any confusion.
The Family Word Finder, a Reader‘s Digest publication, says, “Flammable has now replaced its older synonym inflammable [from Latin inflammare, to kindle) in technical and commercial usage, where the word FLAMMABLE on a dangerously combustible product is thought to serve as a more unmistakable warning.”
2. Descriptive of warmth and intensity without violence, and suggests fluent verbal expressions: Tom loved June so much that he shouted out in an impassioned and emotional way that he would love her for ever and ever!
3. Characteristic of an oration or of a speech that is fervent, fiery, and stirring: Janet gave a very impassioned talk at the meeting about preserving the wildlife area outside the town instead of building the factory, which only a few wanted.
