erect vs knock down

erect

verb
  • To cause to stand up or out. 

  • To animate; to encourage; to cheer. 

  • To spin up and align to vertical. 

  • To lift up; to elevate; to exalt; to magnify. 

  • To raise and place in an upright or perpendicular position; to set upright; to raise. 

  • To set up or establish; to found; to form; to institute. 

  • To put up by the fitting together of materials or parts. 

  • To enter a state of physiological erection. 

  • To cast or draw up (a figure of the heavens, horoscope etc.). 

  • To set up as an assertion or consequence from premises, etc. 

adj
  • Having an erect penis. 

  • Rigid, firm; standing out perpendicularly, especially as the result of stimulation. 

  • Upright; vertical or reaching broadly upwards. 

  • Watchful; alert. 

  • Elevated, as the tips of wings, heads of serpents, etc. 

knock down

verb
  • To hit or knock (something or someone), intentionally or accidentally, so that it falls. 

  • To drink fast. 

  • To disassemble for shipment. 

  • To reduce the price of. 

  • To demolish. 

  • To approve a drinking toast by banging glasses on the table. 

  • At an auction, to declare (something) sold with a blow from the gavel. 

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