He took off the plain robe, put on the black one and went back.
Tips
history
Not a free word now; it survives in literary set phrases — 缁衣 (a monk's robe) and 缁素 (clergy and laity, literally black-and-white). The right side 甾 is the phonetic, also seen in 辎 and 锱.
culture
Because monks wore 缁 black, 缁衣 became a poetic name for the Buddhist clergy, contrasted with the white 素 of lay people.
