“When Jessica said that my performance at the karaoke bar had been incredible, I was incredulous."
I hope Jessica was using “incredible" in the casual sense of “unbelievably good" but I knew I used “incredulous" to mean “unbelieving, skeptical," which is the only standard usage for this word.
The other day I heard a film reviewer praise a director because he created “incredible characters," which would literally mean unbelievable characters.
What the reviewer meant to say, of course, was precisely the opposite: characters so lifelike as to seem like real people. Intensifiers and superlatives tend to get worn down quickly through overuse and become almost meaningless, but it is wise to be aware of their root meanings so that you don’t unintentionally utter absurdities.
“Fantastic" means “as in a fantasy" just as “fabulous" means “as in a fable."
A “wonderful" sight should make you pause in wonder (awe).
Some of these words are worn down beyond redemption, however.
For instance, who now expects a “terrific" sight to terrify?