pejoration vs rotting

pejoration

noun
  • The act or process of becoming worse; worsening or degeneration. 

  • The process by which a word acquires a more negative meaning over time. 

rotting

noun
  • The process by which something rots. 

  • Material that has rotted. 

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