corrosion vs pejoration

corrosion

noun
  • The gradual destruction or undermining of something. 

  • Erosion by chemical action, especially oxidation. 

  • A substance (such as rust) so formed. 

  • The act of corroding or the condition so produced. 

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. 

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