backset vs lowering

backset

noun
  • Whatever is thrown back in its course, such as water. 

  • A check; a relapse; a discouragement; a setback. 

verb
  • To plow again in the fall; said of prairie land broken up in the spring. 

lowering

noun
  • The act of something being lowered. 

adj
  • Dark and menacing. 

  • Lurking, skulking, menacing. 

  • That lowers or frowns. 

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