gibber vs potsherd

gibber

noun
  • A stone or rock, of chalcedony or similar mineral, found strewn over arid regions of inland Australia; a gibber stone. 

  • Gibberish, unintelligible speech. 

  • A balky horse. 

verb
  • To jabber, talk rapidly and unintelligibly or incoherently. 

potsherd

noun
  • A piece of ceramic from pottery, often found on an archaeological site. 

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