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).
During the Heian period, colors such as ōtan (yellow-red) and deep purple were designated as forbidden colors.
Compound of 禁 (prohibition) and 色 (color). The term originates from the Heian-period court system that regulated attire based on rank.