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.
ガット is a modern loanword from English 'gut', often used for sports racket strings, while 天蚕糸 is the traditional Japanese term for the material.
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.