Chou Collection, Upper Volume
Radical: Mouth (kǒu)
Character: Yu
Kangxi strokes: 16
Page 211, Entry 05
Tang Rhyme (Tangyun) and Rhyme Collection (Yunhui) state the pronunciation is yu (falling-rising tone). Rhyme Collection (Jiyun) states the pronunciation is yu (falling-rising tone).
Explaining Graphs and Analyzing Characters (Shuowen) states it refers to the appearance of a group of elk gathered together.
Book of Odes (Shijing), Greater Odes (Daya): "The female elk gather in groups."
The Commentary (Zhuan) notes that the term signifies a multitude. It is also written in a variant form (yu).
Additionally, Extended Rhymes (Guangyun) notes that the term refers to an appearance of smiling. Rhyme Collection (Jiyun) notes it is sometimes written in a variant form (yu).