explain vs overwhelm

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. 

overwhelm

verb
  • To overpower emotionally. 

  • To cause to surround, to cover. 

  • To engulf, surge over and submerge. 

  • To overpower, crush. 

noun
  • The state or condition of being overwhelmed. 

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