fink vs roper

fink

noun
  • An informer. 

  • A strikebreaker. 

  • A contemptible person. 

  • Any of several birds in the family Ploceidae native to southern Africa. 

verb
  • To betray a trust; to inform on. 

roper

noun
  • An undercover informer. 

  • One who ropes goods; a packer. 

  • Synonym of outside man (“accomplice who locates a mark to be swindled by a confidence trickster”) 

  • Any of a variety of monsters with tentacles that they use to capture victims. 

  • A person hired by a gambling establishment to locate potential customers and bring them in. 

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