clench vs myoclonus

clench

noun
  • A tight grip. 

  • A local chapter of the Church of the SubGenius parody religion. 

  • A seal that is applied to formed thin-wall bushings. 

verb
  • To close tightly. 

  • To grip or hold fast. 

myoclonus

noun
  • The brief, involuntary twitching of a muscle or group of muscles. 

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