incentive vs penalty

incentive

noun
  • A bonus or reward, often monetary, to work harder. 

  • Something that motivates, rouses, or encourages. 

adj
  • Inciting; encouraging or moving; rousing to action; stimulating. 

  • Serving to kindle or set on fire. 

penalty

noun
  • A disadvantageous consequence of a previous event. 

  • A punishment for an infraction of the rules, often in the form of being removed from play for a specified amount of time. 

  • A legal sentence. 

  • A punishment for violating rules of procedure. 

  • A direct free kick from the penalty spot, taken after a defensive foul in the penalty box; a penalty kick. 

  • A payment forfeited for an early withdrawal from an account or an investment. 

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