Guo Pu
The oldest Chinese dictionary, the ca. 3rd century BCE "Erya" says "didong" was called "yu" "rain sacrifice", defines it as "hong" "rainbow", and says "ni" "secondary rainbow" was called "qie'er" "lift/carry two." The commentary of Guo Pu notes rainbows were called "yu" in Jiangdong (present day Jiangsu and Zhejiang), and gives additional names of "meiren" "beautiful woman" and "xiyi" "split cover/screen".