monotone vs nugatory

monotone

adj
  • Being, or having the salient properties of, a monotone function. 

  • Having a single unvaried pitch. 

noun
  • A piece of writing in one strain throughout. 

  • A single unvaried tone of speech or a sound. 

verb
  • To speak in a monotone. 

nugatory

adj
  • Trivial, trifling or of little importance. 

  • Having no force, inoperative, ineffectual. 

  • Removable from a computer program with safety, but harmless if retained. 

  • Ineffective, invalid or futile. 

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