amplify vs redouble

amplify

verb
  • To render larger, more extended, or more intense. 

  • To add content that is not present in the source text to the target text, usually to improve the fluency of the translation. 

  • To increase the amplitude of something, especially of an electric current. 

  • To enlarge by addition or commenting; to treat copiously by adding particulars, illustrations, etc.; to expand. 

redouble

verb
  • To double, especially to double again; to increase considerably; to multiply; to intensify. 

  • To become twice as big. 

  • To double an opponent's doubling bid. 

  • To double again what was reduced to a single state. 

noun
  • An optional bid made by the side currently holding the highest bid for the contract, after the opposing side has doubled. 

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