a tough string or thread usually made from the dried intestines of sheep, horses, etc. and used for surgical sutures, for stringing tennis rackets, etc.
Origin:
parallel with Du kattedarm, but ? altered by assoc. with cat < kit gut < obs. kit, fiddle (< ? cithara) + gut
See catgut in American Heritage Dictionary 4
noun
A tough thin cord made from the treated and stretched intestines of certain animals, especially sheep, and used for stringing musical instruments and tennis rackets and for surgical ligatures.