Obscure Roman numerals (3)
I believe the answer is:
dim
'obscure' is the definition.
(I've seen this before)
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 "Darken" , "Not bright, poorly lit" , "Without much light" , "Vague" , "out of mind?" .)