incentive vs shackle

incentive

noun
  • Something that motivates, rouses, or encourages. 

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

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

  • Serving to kindle or set on fire. 

shackle

noun
  • A link for connecting railroad cars; a drawlink or draglink. 

  • A restraint on one's action, activity, or progress. 

  • A length of cable or chain equal to 12+¹⁄₂ fathoms or 75 feet, or later to 15 fathoms. 

  • A U-shaped piece of metal secured with a pin or bolt across the opening, or a hinged metal loop secured with a quick-release locking pin mechanism. 

  • A fetter-like band worn as an ornament. 

  • A restraint fit over a human or animal appendage, such as a wrist, ankle or finger; normally used in pairs joined by a chain. 

verb
  • To render immobile or incapable; to inhibit the progress or abilities of. 

  • To shake, rattle. 

  • To restrain using shackles; to place in shackles. 

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