carbuncle vs knop

carbuncle

noun
  • An abscess larger than a boil, usually with one or more openings draining pus onto the skin. It is usually caused by staphylococcal infection. 

  • An unpopular or ugly building; an eyesore. 

knop

noun
  • A knob, usually ornamental 

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