boon vs fringe benefit

boon

noun
  • A good thing; a blessing or benefit; a thing to be thankful for. 

  • The woody portion of flax, separated from the fiber as refuse matter by retting, braking, and scutching. 

  • An unpaid service due by a tenant to his lord. 

adj
  • gay; merry; jovial; convivial. 

fringe benefit

noun
  • A benefit received in addition to the normal benefits of holding a job, or, by extension, any relationship to the source of the benefit. 

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