Yes, "unclever" is a word that means not clever or lacking intelligence. It is not as commonly used as its synonym "unintelligent" but can still be found in the dictionary.
There is a word unclever which is rarely used.The opposite of clever (bright, smart) would be dull, foolish, or unintuitive.
STUPID - dull, unclever
Opposites could be unclever, unskilled, or dim-witted.
to exist = to be = esse
To exist is "exister" in French.
The word knowned does not exist. The words known and reknown definitely do exist.
A word that does not exist.
is, are
No
This is word does not exist.
no