conceive vs unfathom

conceive

verb
  • To understand (someone). 

  • To generate or engender; to bring into being. 

  • To develop an idea; to form in the mind; to plan; to devise; to originate. 

  • To become pregnant (with). 

unfathom

verb
  • to come to comprehend; demystify. 

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