busk vs retain

busk

verb
  • To solicit money by entertaining the public in the street or in public transport. 

  • To tack, cruise about. 

noun
  • A strip of metal, whalebone, wood, or other material, worn in the front of a corset to stiffen it. 

  • A corset. 

retain

verb
  • To keep in one's pay or service. 

  • To employ by paying a retainer. 

  • To hold back (a pupil) instead of allowing them to advance to the next class or year. 

  • To keep in possession or use. 

  • To hold secure. 

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