Barely discernible Roman numerals (3)
I believe the answer is:
dim
'barely discernible roman' is the definition.
Although both the answer and definition are adjectives, I don't understand how they can define each other.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for dim that I've seen before include "Opaque, not bright" , "Not bright or distinct" , "Slow to learn" , "Darken" , "Lacking in light" .)