astringe vs clench

astringe

verb
  • To bind by moral or legal obligation. 

clench

verb
  • To grip or hold fast. 

  • To close tightly. 

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. 

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