idle vs monotone

idle

adj
  • Of no importance; useless; worthless; vain; trifling; thoughtless; silly. 

  • Not engaged in any occupation or employment; unemployed; inactive; doing nothing in particular. 

  • Not being used appropriately; not occupied; (of time) with no, no important, or not much activity. 

  • Averse to work, labor or employment; lazy; slothful. 

noun
  • An idle game. 

  • The lowest selectable thrust or power setting of an engine. 

  • The state of idling, of being idle. 

  • An idle animation. 

verb
  • To spend in idleness; to waste; to consume. 

  • Of an engine: to run at a slow speed, or out of gear; to tick over. 

  • To lose or spend time doing nothing, or without being employed in business. 

monotone

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

  • Having a single unvaried pitch. 

verb
  • To speak in a monotone. 

noun
  • A piece of writing in one strain throughout. 

  • A single unvaried tone of speech or a sound. 

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