diatribe vs pep talk

diatribe

noun
  • A speech or writing which bitterly denounces something. 

  • An abusive, bitter, verbal attack or criticism: denunciation. 

  • A prolonged discourse. 

pep talk

noun
  • A rallying speech made to instill enthusiasm and boost confidence 

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