The flow of air relative to an aircraft, caused by its motion through the air.
The direction from which the supporting column of air is coming. When you exit an aircraft that is traveling forward, the relative wind direction comes from an angle, down and from the direction of the aircraft's flight.
the velocity and direction of the air flowing toward the airfoil/wing/etc that is not influenced by the airfoil etc. We call that V(infinity) in aero terms. I would like to be able to write a capital V with a sideways "8" for infinity because that is standard but I'll abbreviate here with Vi. For a whole aircraft it is the opposite from the direction the aircraft is flying in ( not where the propellor points but the direction that the center of gravity is moving).