assart vs lea

assart

noun
  • Forest land cleared for agriculture. 

verb
  • To clear forest land for agriculture; remove stumps. 

lea

noun
  • An open field, meadow. 

  • Any of several measures of yarn; for linen, 300 yards (275 m); for cotton, 120 yards (110 m). 

  • A set of warp threads carried by a loop of the heddle. 

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