continuant vs unceasing

continuant

adj
  • Continuing; prolonged; sustained. 

noun
  • An endurant. 

  • A determinant formed from a tridiagonal matrix. 

  • A linguistic sound other than a stop. 

unceasing

adj
  • continuous; continuing indefinitely without stopping 

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