explain vs throw off

explain

verb
  • To make plain, manifest, or intelligible; to clear of obscurity; to illustrate the meaning of. 

  • To give a valid excuse for past behavior. 

  • To make something plain or intelligible. 

throw off

verb
  • To give forth in an unpremeditated manner. 

  • To expel, reject, or renounce. 

  • Of a horse, to eject its rider. 

  • To introduce errors or inaccuracies; to skew. 

  • To confuse; especially, to lose a pursuer. 

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