noun
Heian-era color restrictions by court rank
Historical term referring to the system that prohibited certain colors from being worn by courtiers below a specific rank. Often contrasted with 許し色 (permitted colors).
平安時代には、禁色として黄丹や深紫などが定められていた。
During the Heian period, colors such as ōtan (yellow-red) and deep purple were designated as forbidden colors.