decrease vs shorten

decrease

verb
  • To make (a quantity) smaller. 

  • Of a quantity, to become smaller. 

noun
  • A reduction in the number of stitches, usually accomplished by suspending the stitch to be decreased from another existing stitch or by knitting it together with another stitch. See Decrease (knitting). 

  • An amount by which a quantity is decreased. 

shorten

verb
  • To reduce or diminish in amount, quantity, or extent; to lessen. 

  • To take in the slack of (a rope). 

  • To reduce (sail) by taking it in. 

  • To become shorter. 

  • To make shorter; to abbreviate. 

  • To make short or friable, as pastry, with butter, lard, etc. 

  • To make deficient (as to); to deprive (of). 

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