chiller vs difficulty

chiller

noun
  • A frightening dramatic work, such as a book or film 

  • A machine that removes heat from the working fluid in a refrigeration cycle 

  • a heat exchanger between a coolant and a refrigerant, to transfer heat from the coolant loop into the refrigeration system 

  • a machine that produces cold air, either for air conditioning, to prepare chilled foods etc. 

difficulty

noun
  • That which cannot be easily understood or believed. 

  • Physical danger from the environment, especially with risk of drowning 

  • An obstacle that hinders achievement of a goal. 

  • The state of being difficult, or hard to do. 

  • An objection. 

  • An awkward situation or quarrel. 

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