inexertion vs lightness

inexertion

noun
  • Lack of exertion or effort; indolence; laziness. 

lightness

noun
  • Agility of movement. 

  • Levity, frivolity; inconsistency. 

  • The state of having little (or less) weight, or little force. 

  • the relative whiteness or transparency of a colour 

  • The product of being illuminated. 

  • Freedom from worry. 

  • the condition of being illuminated 

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