Why is only yellow writen 色 with behind its color?
learning the colors right now. But a lot of times is see that Yellow is written 黄色. But why does only yellow have the 色 (iro) behind it. 色 mean color right? but why is it not 赤色 akairo or 青色 aoiro but only with yellow it is kiiro. I'm confused about that. Is there a explanation?

Question

Why is only yellow writen 色 with  behind its color?
learning the colors right now. But a lot of times is see that Yellow is written 黄色. But why does only yellow have the 色 (iro) behind it. 色 mean color right? but why is it not 赤色 akairo or 青色 aoiro but only with yellow it is kiiro. I'm confused about that. Is there a explanation?

Answer

it's same with that you say tuna fish but never say pork pig

Answer

http://www.italki.com/answers/question/150708.htm Probably the answers and comments in this thread might be help

Answer

Because the rest of the colors are -ku adjectives on their own and need no other Kanji. Yellow is not a -ku adjective so it needs iro.

All of the colors (that are in Kanji) can work with iro if you remove the -I. So red can be akai or akairo. ( the I is not sport of the Kanji so it is omitted.)