I saw the word coruscating and its misuse being discussed on a forum to which I belong, and I suddenly realised that the word people had been confusing it with was excoriating. Cue a Troublesome Pair! Two quite difficult words, but we’re up for them, aren’t we!
To coruscate means to flash or sparkle, so coruscating wit is sparkling wit. Because people only have a vague idea that it has something to do with wit, they seem to have changed its meaning to be something harsher, almost a flaying kind of idea, and I’ve heard this a few times myself, but, for example, criticism can’t be coruscating – it means sparkling, nothing to do with harshness, ripping to shreds, etc.
To excoriate, however, does mean to criticise severely, so although it’s a bit of a tautology (saying the same thing twice in one phrase), you can have excoriating criticism. And, excitingly for my half-remembered meaning of difficult words, it has a medical sense meaning to damage or remove part of the skin!
So, now you know. Go on: use one of them in your conversation today!