extend vs intensify

extend

verb
  • To increase in extent. 

  • To reenlist for a further period. 

  • To increase in quantity by weakening or adulterating additions. 

  • To value, as lands taken by a writ of extent in satisfaction of a debt; to assign by writ of extent. 

  • To straighten (a limb). 

  • Of a class: to be an extension or subtype of, or to be based on, a prototype or a more abstract class. 

  • To cause to increase in extent. 

  • To cause to last for a longer period of time. 

  • To possess a certain extent; to cover an amount of space. 

  • To bestow; to offer; to impart; to apply. 

intensify

verb
  • To become intense, or more intense; to act with increasing power or energy. 

  • To render more intense 

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