robber vs ruffian

robber

noun
  • A person who robs. 

  • An animal who robs. 

ruffian

noun
  • A scoundrel, rascal, or unprincipled, deceitful, brutal and unreliable person. 

verb
  • To play the ruffian; to rage; to raise tumult. 

adj
  • Brutal; cruel; savagely boisterous; murderous. 

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