encumbrance vs monkey wrench

encumbrance

noun
  • Something that encumbers; a burden that must be carried. 

  • An interest, right, burden, or liability attached to a title of land, such as a lien or mortgage. 

  • One who is dependent on another. 

verb
  • To apply an encumbrance to (property, etc.). 

monkey wrench

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

  • A wrench (spanner) with an adjustable jaw. 

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