angle of attack
In the theory of airplane wings, the angle of attack is the acute angle between the wing profile (roughly, measured along its bottom) and the wing's motion relative to the surrounding air. In the case of a rocket rising through the atmosphere, it is the angle between the long axis of the rocket and the direction of the air flowing past it.
The angle of attack changes during a flight as the pilot changes the direction of the aircraft. It is one of the factors that determines the aircraft's rate of speed through the air. Depending on the angle of attack, there will be a force backward (induced drag) and a force upward (lift). The amount of force depends on the angle of attack. If the angle of attack is small, the drag and lift are comparatively small. Increasing the angle of attack increases lift up to a point; however, too high an angle of attack results in a loss of lift and can cause an aircraft to stall.