You Collection, Middle Volume
Radical: Red (chì)
Character: xi
Kangxi stroke count: 13
Page 1214, Entry 06
Pronounced xu (rising tone).
According to the Explaining Graphs and Analyzing Characters (Shuowen Jiezi), it means deep red.
In the Elegies of Chu (Chuci), specifically the Great Summons (Da Zhao) section: There are cold mountains to the north, towering and crimson. The commentary states: xi describes the appearance of a red color where no plants or trees grow.
In Zuo Si’s Rhapsody on the Capital of Shu (Shudu Fu): Cinnabar and sand emerge crimson and glowing from the slopes. The commentary states: xi describes the appearance of red.
Also, according to the Jade Compendium (Yupian), it means red and white. It also describes the appearance of anger.
According to the Collection of Rhymes (Jiyun), also pronounced he (entering tone). The meaning is the same.