Knock down
Knock down , noun
1.
To strike down; to fell; to prostrate by a blow or by blows; as, to knock down an assailant.
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.
3.
To take apart; to disassemble; as, to knock down a rifle for cleaning.
4.
To reduce or discount the price of; as, the dresses were knocked down to twenty dollars.
5.
To earn (an income).
plumbers who knock down over a hundred thousand a year.