expect vs understand

expect

verb
  • To predict or believe that something will happen 

  • To consider obligatory or required. 

  • To consider reasonably due. 

  • To be pregnant, to consider a baby due. 

understand

verb
  • To believe, to think one grasps sufficiently despite potentially incomplete knowledge. 

  • To stand underneath, to support. 

  • To grasp a concept fully in one's mind, especially (of words, statements, art, etc.) to be aware of the meaning of and (of people) to be aware of the intent of. 

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