1 informal (of a price) very low.
[used earlier to refer to reserve prices set at an auction]
2capable of knocking down or overwhelming someone or something:repeated knockdown blows (of furniture) easily dismantled and reassembled.
an act of knocking an opponent down. (also knockdown pitch) Baseball a pitch aimed so close to the body that the batter must drop to the ground to avoid being hit:the catcher gave the sign for a knockdown pitch Sailing an instance of a vessel being knocked on its side by the force of the wind.