gangster vs mugger

gangster

noun
  • A member of a criminal or street gang. 

  • A member of a professional criminal organization; a racketeer. 

verb
  • To act like a gangster; to commit street crime or run a racket. 

mugger

noun
  • A person who assaults and robs others, especially in a public place. 

  • A large crocodile, Crocodylus palustris, of southwest Asia, having a very broad wrinkled snout. 

  • A person who makes exaggerated faces, as a performance; a gurner. 

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