hashtag vs signify

hashtag

verb
  • To label (a message) with a hashtag. 

noun
  • A metadata tag, signaled by a preceding hash sign (#), used to label content. 

  • The hash sign itself, when used as part of a hashtag. 

signify

verb
  • To create a sign out of something. 

  • To show one’s intentions with a sign etc.; to indicate, announce. 

  • To mean; to betoken. 

  • To make a difference; to matter (in negative or interrogative expressions). 

  • To give (something) a meaning or an importance. 

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