nod vs rubber stamp

nod

verb
  • To make a mistake by being temporarily inattentive or tired 

  • To signify by a nod. 

  • To incline the head up and down, as to indicate agreement. 

  • To allude to something. 

  • To sway, move up and down. 

  • To briefly incline the head downwards as a cursory greeting. 

  • To fall asleep while under the influence of opiates. 

  • To gradually fall asleep. 

  • To head; to strike the ball with one's head. 

noun
  • A nomination. 

  • An instance of inclining the head up and down, as to indicate agreement, or as a cursory greeting. 

  • Approval. 

  • A reference or allusion to something. 

rubber stamp

verb
  • To process, approve or decide matters routinely rather than through careful consideration. 

noun
  • A person or organisation that approves, routinely or as a formality, matters decided by some other person or organisation. 

  • A piece of rubber or similar material with a design or text carved or molded for the purpose of transferring ink or dye to imprint that design on another object. 

adj
  • Of a person, organisation, or process, making decisions or approving matters routinely or without real power. 

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