slacken vs uncrisp

slacken

verb
  • To make slack, less taut, or less intense. 

  • To gradually decrease in intensity or tautness; to become slack. 

  • To deprive of cohesion by combining chemically with water; to slake. 

uncrisp

verb
  • To become less or not crisp. 

adj
  • Not possessing firmness and freshness or brittleness (especially of foods). 

  • Not quick, precise, accurate or well-defined. 

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