silkworm gut; catgut
A strong, translucent thread made from the silk glands of silkworms, traditionally used for fishing lines, surgical sutures, and musical instrument strings. The term 'catgut' is a historical English name, though the material is not from cats.
Silkworm gut is used for fishing lines and surgical sutures.
昔のテニスラケットには天蚕糸が張られていた。
Old tennis rackets were strung with gut.
From 天蚕 (てんさん, 'wild silkworm') + 糸 (いと, 'thread'), with the reading てぐす likely derived from てんぐす, a contraction of 天蚕糸. The exact historical sound change is uncertain.