bowstring vs stringed instrument

bowstring

noun
  • The string of an archer's bow. 

  • The string of an archer's bow, as used by the Turks for strangling offenders. 

verb
  • To strangle with a bowstring. 

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 bowstring and stringed instrument occurred in a corpus of books? (source: Google Ngram Viewer )