'Knock down' definitions:

Definition of 'knock down'

(from WordNet)
verb
Cause to come or go down; "The policeman downed the heavily armed suspect"; "The mugger knocked down the old lady after she refused to hand over her wallet" [syn: down, knock down, cut down, push down, pull down]
verb
Knock down with force; "He decked his opponent" [syn: deck, coldcock, dump, knock down, floor]
verb
Shatter as if by explosion [syn: blast, knock down]

Definition of 'Knock down'

From: GCIDE
  • Knock down \Knock" down`\, n.
  • 1. To strike down; to fell; to prostrate by a blow or by blows; as, to knock down an assailant. [1913 Webster]
  • 2. To assign to a bidder at an auction, by a blow or knock of the auctioneer's hammer; to sell at an auction; as, the vase was knocked down at two thousand dollars. [1913 Webster +PJC]
  • 3. To take apart; to dissassemble; as, to knock down a rifle for cleaning. [PJC]
  • 4. To reduce or discount the price of; as, the dresses were knocked down to twenty dollars. [PJC]
  • 5. To earn (an income). "plumbers who knock down over a hundred thousand a year." [PJC]

Synonyms of 'knock down'

From: Moby Thesaurus