burn off vs unblock

burn off

verb
  • To use up a resource in a nonproductive manner. 

  • To dispose of (unusable explosive natural gas from an oil well) by burning it as it emerges from the well. 

  • To dissipate as the result of heat. 

  • To fill (low-value air time) with programming not suitable for its original purpose. 

  • To cause to dissipate by applying heat. 

  • To fail due to overheating. 

  • To expend energy resulting from metabolizing food. 

  • Cause to waste energy. 

unblock

verb
  • To free or make available. 

  • To remove or clear a block or obstruction from. 

  • In whist, to throw away a high card so as not to interrupt one's partner's long suit. 

  • To enable communication again, via telephone, instant messaging, etc., with (somebody previously blocked). 

noun
  • The removal of a block or blockage. 

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