In the Jiyun (Jiyun), the character is used for phonetic annotation, pronounced gou (falling tone). The Yupian (Yupian) explains it as "nighttime." Quoting from the Book of Odes (Shijing), "zhong gou zhi yan," meaning "words spoken in the middle of the night." Furthermore, the Zhengzitong (Zhengzitong) explains it as a secluded place deep within a house, originally written as the character gou.