continuant vs sibilation

continuant

noun
  • A linguistic sound other than a stop. 

  • An endurant. 

  • A determinant formed from a tridiagonal matrix. 

adj
  • Continuing; prolonged; sustained. 

sibilation

noun
  • A hissing sound. 

  • From the shadows emanated a hushed sibilation. 

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