plateau vs unbend

plateau

verb
  • (of a varying quantity) To reach a stable level after a period of increase; to level off. 

noun
  • A comparatively stable level after a period of increase. 

  • A notable level of attainment or achievement. 

  • A largely level expanse of land at a high elevation; tableland. 

unbend

verb
  • To release (a load) from a strain or from exertion; to set at ease for a time; to relax. 

  • To remove a bend so as to make, or allow to become, straight. 

  • To cast loose or untie 

  • To cease to be bent; to become straight. 

  • To relax in exertion, attention, severity, or the like 

  • To unfasten sails from the spars or stays to which are attached for use. 

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