Chen Collection, Middle Volume
Radical: Tree (mù)
Si
Kangxi Strokes: 9
Page 521, Entry 08
Pronounced si (falling tone)
According to the Explaining Graphs and Analyzing Characters (Shuowen Jiezi), it refers to a type of spoon.
Book of Rites (Liji), record of protocol: The steward fills the goblet with sweet wine and places a spoon (si) on it.
Rites of Zhou (Zhouli), notes by the Jiangren: Using a spoon (si) to drink sweet wine is for dregs. Not using a spoon is for clear liquid. Also, there is the horn spoon (si), used in funeral rites.
Book of Rites (Liji), notes on funeral rites: Made of horn, six inches long, with both ends curved.
Textual Research: In the Book of Rites (Liji), regarding the protocol section, the original text reads fills the goblet with sweet wine. Following the original text, the character for at is corrected to with.