Noun

1. An act of knocking down or the condition of being knocked down.
2. An overwhelming blow.
3. A genetically modified organism that carries one or more genes in its chromosomes that has been made less active or had its expression reduced.
4. The use of a reagent such as an oligonucleotide with sequence complementary to an active gene or its mRNA transcript, to interfere with the expression of said gene.
5. The condition of a sailboat being pushed abruptly to horizontal, with the mast parallel to the water surface.

Adjective

1. powerful enough to overwhelm or knock down
2. reduced in price