Mao Collection, Middle Volume. Radical: Hand (shǒu). Kangxi strokes: 20. Page 462, Entry 33.
According to the Collection of Rhymes (Jiyun) and the Rhyme Collection (Yunhui), the pronunciation is huan (falling-rising tone). It is read like the rising tone of huan. It refers to a wooden fence. In the Records of the Grand Historian (Shiji), Jia Yi's Fu-poem on the Owl says: restrained by the world and bound by customs, trapped like a prisoner.
Furthermore, according to the Orthography (Zhengyun), the pronunciation is wan (falling-rising tone), with the same meaning.
According to the Guide to Correct Characters (Zhengzitong), it refers to detention or binding. Prisons were also called round-earths (huan-tu), designed to prevent prisoners from escaping. The term for this character is interchangeable with the term for round (huan).