boon vs convulsion

boon

adj
  • gay; merry; jovial; convivial. 

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

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

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

convulsion

noun
  • An uncontrolled fit, as of laughter; a paroxysm. 

  • An intense, paroxysmal, involuntary muscular contraction. 

  • Violent turmoil. 

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