Dear N:

You wrote:

The careful meaning of “mediocre” is average, but some people use it to mean “bad”.

Is the way the word “careful” has been used in the above sentence acceptable?

I have no idea what that sentence means. People are careful, not meanings.

Are you trying to use the word “literal”? “The literal meaning of ‘mediocre’ is ‘average,’ but the word has a negative connotation.”