incentive vs tonic

incentive

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

  • Serving to kindle or set on fire. 

noun
  • Something that motivates, rouses, or encourages. 

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

tonic

adj
  • Restorative, curative or invigorating. 

  • Of or relating to tones or sounds; specifically (phonetics, dated) being or relating to a speech sound made with tone unmixed and undimmed by obstruction, i.e. a vowel or diphthong. 

  • Pertaining to tension, especially of muscles. 

  • In a state of continuous unremitting action. 

  • Pertaining to or based upon the first note of a diatonic scale. 

  • Pertaining to the accent or stress in a word or in speech. 

noun
  • A substance with medicinal properties intended to restore or invigorate. 

  • Someone or something that revitalises or reinvigorates. 

  • The first note of a diatonic scale; the keynote. 

  • The triad built on the tonic note. 

  • Tonic water. 

  • Any of various carbonated, non-alcoholic beverages; soda pop. 

  • A tonic element or letter; a vowel or a diphthong. 

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