decrease vs decrement

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. 

decrement

verb
  • To decrease a value by a basic quantity unit. 

noun
  • A small quantity removed or lost. One of a series of regular subtractions. 

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