Since I cant type just one letter, I believe the answer you are searching for is "A"
<span>Proper adjectives have their initial letter capitalised,
for example American - derived from a proper noun America - or Victorian - derived from (queen) Victoria.
Common adjectives, on the contrary, don't have </span><span>their initial letter capitalised</span>, for example green, empty, colourful. Just remember that "common adjective" is not a scientific term used by linguists, it is informal.