continuant vs invariant

continuant

adj
  • Continuing; prolonged; sustained. 

noun
  • An endurant. 

  • A determinant formed from a tridiagonal matrix. 

  • A linguistic sound other than a stop. 

invariant

adj
  • not varying; constant 

  • Neither covariant nor contravariant. 

  • Unaffected by a specified operation (especially by a transformation) 

noun
  • An invariant quantity, function etc. 

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