forum vs think-in

forum

noun
  • A gathering for the purpose of discussion. 

  • A place for discussion. 

  • An Internet message board where users can post messages regarding one or more topics of discussion. 

  • A form of discussion involving a panel of presenters and often participation by members of the audience. 

  • A square or marketplace in a Roman town, used for public business and commerce. 

think-in

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