I can't claim to be an expert, but this is likely correct. The native Japanese words for color (shiro, kuro, aka, ao, midori etc) don't use the -色/iro suffix.
Japanese has the cool feature that you can clearly identify siro/kuro/aka/ao (a fairly typical four-way white/black/red-yellow/blue-green distinction) as the most basic colour words with relatively little diachronic analysis: they're the ones that stand alone in the rather limited class of 形容詞 ("i-adjective") stems.
You can almost trace the development of colour terms through the vocabulary strata...
Note that you still can use the the iro/color suffix for aka (red), ao (blue), midori (green), you just don't have to and they also function as standalone adjectives.
E.g. akai (赤い) -- red (adjective) vs akairo (赤色) -- the color red (noun)
compare: chaiiroi (茶色い) -- light brown (adjective) vs chaiiro (茶色) the color light brown (noun) -- literally "tea color"
naniwaduni|5 years ago
You can almost trace the development of colour terms through the vocabulary strata...
EE84M3i|5 years ago
E.g. akai (赤い) -- red (adjective) vs akairo (赤色) -- the color red (noun)
compare: chaiiroi (茶色い) -- light brown (adjective) vs chaiiro (茶色) the color light brown (noun) -- literally "tea color"