redouble vs weaken

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. 

weaken

verb
  • To make weaker or less strong. 

  • To become weaker or less strong. 

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