The term downwash has two nearly unrelated meanings within the field of aerodynamics.

One meaning, used most often by non-engineers, refers to the forcing of air downward during the creation of lift. This usage is most common with regard to helicopters where the effect is most dramatic.

The other meaning, used most often by engineers, refers to the flow of air over the tip of a wing and is a critical component in the creation of wing tip vortices.