Chou Collection, Upper Volume Radical: Mouth (kǒu) 嗉 Kangxi stroke count: 13 Page 202, Entry 13 Pronounced su. Book of Rites (Erya), Explanation of Birds: The throat of a bird, and its food storage pouch is called a su. Commentary: A su is the place where birds store food; it is also known as a su. Also refers to a star constellation name. Book of Han (Qianhan), Treatise on Astronomy: The Zhang constellation and the Su constellation govern matters concerning the entertaining of guests.