detective vs roper

detective

noun
  • A person employed to find information not otherwise available to the public. 

  • A police officer who looks for evidence as part of solving a crime; an investigator. 

adj
  • Employed in detecting. 

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 detective and roper occurred in a corpus of books? (source: Google Ngram Viewer )