keep vs substitute

keep

verb
  • To supply with necessities and financially support (a person). 

  • To refrain from freely disclosing (a secret). 

  • To continue in (a course or mode of action); to not intermit or fall from; to uphold or maintain. 

  • To remain edible or otherwise usable. 

  • To remain in a state. 

  • To observe; to adhere to; to fulfill; to not swerve from or violate. 

  • To raise; to care for. 

  • To have habitually in stock for sale. 

  • To act as wicket-keeper. 

  • To enter (accounts, records, etc.) in a book. 

  • To maintain the condition of; to preserve in a certain state. 

  • To restrain. 

  • To maintain (an establishment or institution); to conduct; to manage. 

  • To watch over, look after, guard, protect. 

  • To maintain possession of. 

  • To record transactions, accounts, or events in. 

  • To remain faithful to a given promise or word. 

  • To continue. 

noun
  • The state of being kept; hence, the resulting condition; case. 

  • A cap for holding something, such as a journal box, in place. 

  • The food or money required to keep someone alive and healthy; one's support, maintenance. 

  • The main tower of a castle or fortress, located within the castle walls. 

substitute

verb
  • To serve as a replacement (for someone or something). 

  • To remove (a player) from the field of play and bring on another in his place. 

  • To use in place of something else, with the same function. 

  • To use X in place of Y. 

  • To use Y in place of X; to replace X with Y. 

noun
  • A player who is available to replace another if the need arises, and who may or may not actually do so. 

  • A replacement or stand-in for something that achieves a similar result or purpose. 

  • One who enlists for military service in the place of a conscript. 

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