slackness vs slowness

slackness

noun
  • The state of being slack; the quality of having slack. 

  • A subgenre of dancehall music with sexual lyrics. 

  • Vulgarity in West Indian culture. 

slowness

noun
  • The quality or state of being slow. 

  • A unit, the reciprocal of velocity, that delineates the amount of time required for an object to travel a given distance. 

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