tumble vs understand

tumble

verb
  • To fall end over end; to roll over and over. 

  • To smoothe and polish, e.g., gemstones or pebbles, by means of a rotating tumbler. 

  • To muss, to make disorderly; to tousle or rumple. 

  • To obscure the audit trail of funds by means of a tumbler. 

  • To perform gymnastics such as somersaults, rolls, and handsprings. 

  • To have sexual intercourse. 

  • To move or rush in a headlong or uncontrolled way. 

  • To drop rapidly. 

noun
  • A fall, especially end over end. 

  • An act of sexual intercourse. 

  • A disorderly heap. 

understand

verb
  • To stand underneath, to support. 

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

  • 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 tumble and understand occurred in a corpus of books? (source: Google Ngram Viewer )