What is the meaning of knock down?

verb

• Cause to come or go down.
  • usage: "The policeman downed the heavily armed suspect"; "The mugger knocked down the old lady after she refused to hand over her wallet"
  • synonyms: down, cut down, push down, pull down
• Knock down with force.
  • usage: "He decked his opponent"
  • synonyms: deck, coldcock, dump, floor
• Shatter as if by explosion.
  • synonyms: blast