cross-sectional shape of a wing, blade (of a propeller, rotor, or turbine), or sail

An airfoil (in American English, or aerofoil in British English) is the shape of a wing, or blade of a propeller, the blade of a ship's screw or the shape of a sail as seen in cross-section. When moving through a fluid it will provide lift and drag. Lift is not only up, it may be in other directions depending on what it is used for. The airfoil has a rounded leading edge (front edge of the wing) to make the airfoil more insensitive to the angle of attack.

Wing profile vocabulary