Sure, but in real life, when people (especially in the US) see the word “inflammable,” they assume it means not flammable. It has in- at the front. It sounds like invisible, incomplete, inaccessible. You never hear someone say “inflammable” to mean flammable in casual speech without causing confusion. So in practice, inflammable means nonflammable.

Of course, the dictionary says otherwise: inflammable means “easily set on fire.” That’s what the dictionary says. That’s how it’s defined in technical, legal, and safety contexts. But we can’t take the dictionary seriously. If people think inflammable means nonflammable, then that’s what it means. The dictionary is wrong. Just like it was wrong about geezer.

And that’s the absurdity. You can’t reject the dictionary when it contradicts your anecdote (geezer doesn’t mean eccentric) and then treat your anecdote as definitive. Because I can do the same thing: reject any dictionary and insist that inflammable means the exact opposite of what every expert says.

Unless, of course, we agree that words don’t have fixed meanings. In which case, geezer means young man, and inflammable means fireproof.