catgut vs stringed instrument

catgut

noun
  • A cord of great toughness made from the intestines of animals, especially of sheep, used for strings of musical instruments, racquets, sutures etc. 

  • A sort of linen or canvas, with wide interstices. 

  • The material from which such cords are made. 

  • Tephrosia virginiana (goat's rue, devil's shoestring). 

stringed instrument

noun
  • Any of very many musical instruments in which taut strings are plucked, bowed or struck in order to produce a sound 

How often have the words catgut and stringed instrument occurred in a corpus of books? (source: Google Ngram Viewer )