idle vs knock off

idle

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

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

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

noun
  • An idle game. 

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

  • The state of idling, of being idle. 

  • An idle animation. 

adj
  • 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. 

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

knock off

verb
  • To halt one's work or other activity. 

  • To rob. 

  • To defeat. 

  • To have sex with. 

  • To remove, as a discount or estimate. 

  • To make a copy of, as of a design. 

  • To assign (an item) to a bidder at an auction, indicated by knocking on the counter. 

  • To remove by hitting (something, someone) 

  • To kill. 

  • To accomplish hastily. 

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