redoubtable vs tremendous

redoubtable

adj
  • Eliciting respect or fear; imposing; awe-inspiring. 

tremendous

adj
  • Awe-inspiring; terrific. 

  • Notable for its size, power, or excellence. 

  • Extremely large (in amount, extent, degree, etc.) or great 

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