drub vs plow under

drub

verb
  • To defeat someone soundly; to annihilate or crush. 

  • To beat (someone or something) with a stick. 

  • To forcefully teach something. 

  • To criticize harshly; to excoriate. 

noun
  • Carbonaceous shale; small coal; slate, dross, or rubbish in coal. 

plow under

verb
  • To destory (crops) by turning them into the ground with a plow 

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