Which one of these words should not be used in the comparative or superlative degree?

You're likely asking about absolute adjectives. These words describe qualities that cannot be more or less than they already are. Therefore, they don't have comparative or superlative forms.

Here are some examples of absolute adjectives:

* Perfect

* Unique

* Dead

* Round

* Square

* Empty

* Full

* Ultimate

For example:

* It's incorrect to say "more perfect" or "most perfect" because something is either perfect or it isn't.

* Similarly, you wouldn't say "more unique" or "most unique" because something is either unique or it isn't.

To determine the correct answer, you need to provide the list of words you're considering.