inefficient vs monotone

inefficient

adj
  • Incapable of, or indisposed to, effective action; habitually slack or unproductive; effecting little or nothing 

  • Not efficient; not producing the effect intended or desired; inefficacious 

noun
  • A person who cannot or does not work efficiently. 

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. 

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