The word "腱鞘" is formed by combining the character "腱", meaning tendon, which uses the radical "月" to signify its relation to the body and the phonetic component "建" to suggest its pronunciation, with the character "鞘", meaning sheath, which uses the radical "革" to indicate a leather-like covering and the phonetic component "肖" for pronunciation; together, these characters literally denote "tendon sheath", referring to the anatomical structure that encases a tendon.