It seems that watches are often described subjectively and in vague terms using adjectives in an effort to separate them in some way from others.
I find "Rare" to be one of the hardest words to define. It seldom has a starting or ending point, there is no scale or rating for it, remains mostly
in the mind of the viewer on whether it is or isn't, there is no penalty for stating it, and may or may not be true.
While a "rare" find is good, an "extremely rare" find is even better. "Uniquely rare" could be interesting but may not be better than one that's "Supremely rare".
What do you think is the Hardest Word to Define?