add vs weaken

add

verb
  • To summon minions or reinforcements. 

  • To append (e.g. a statement); to say further information; to add on. 

  • To combine elements of (something) into one quantity. 

  • To give by way of increased possession (to someone); to bestow (on). 

  • To make an addition; to augment; to increase; to add on. 

  • To join or unite (e.g. one thing to another, or as several particulars) so as to increase the number, augment the quantity, or enlarge the magnitude, or so as to form into one aggregate. 

  • To sum up; to put together mentally; to add up. 

  • To perform the arithmetical operation of addition. 

noun
  • The addition of a song to a station's playlist. 

  • An act or instance of adding. 

  • An additional enemy that joins a fight after the primary target. 

weaken

verb
  • To make weaker or less strong. 

  • To become weaker or less strong. 

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