encouragement vs monkey wrench

encouragement

noun
  • Words or actions that increase someone's confidence 

  • Something that incites, supports, promotes, protects or advances; incentive 

  • The feeling of being encouraged 

  • The act of encouraging 

monkey wrench

noun
  • An unexpected or troublesome problem, obstacle or dilemma. 

  • A wrench (spanner) with an adjustable jaw. 

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