corroboration vs grounds

corroboration

noun
  • That which corroborates. 

  • The act of corroborating, strengthening, or confirming; addition of strength; confirmation 

grounds

noun
  • Basis or justification for something. 

  • The sediment at the bottom of a liquid, or from which a liquid has been filtered. 

  • The collective land areas that compose a larger area. 

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