翼型或称翼剖面，是指机翼、风帆、螺旋桨、直升机旋翼、涡轮的横截面形状。翼型可以改变力的方向，例如可以把平行方向的推力转换为升力，或是将水平方向的旋转力矩转换为垂直方向的推力。

翼型的升力主要来自翼型的形状和迎角（或称之为攻角），有合适的迎角的翼型会对来流产生扰动，由此产生一个与扰动相反方向的力，称之为气动力。气动力可以被分解为升力和阻力，与来流方向垂直的合力称之为升力，与来流方向平行的的合力称之为阻力。大多数翼型需要在正的迎角下才产生升力，但是有弯度翼型在迎角为0的情况下也能产生升力。来流在受到扰动后，在翼型表面附近出现了弯曲的流线，因此在翼型的两个表面产生了不同的压力。根据伯努利定律，在流速快的地方压力小，流速慢的地方压力大，因此，可以根据上下表面的流速差来计算翼型的升力。实际上,引入环量的概念后，根据库塔-儒可夫斯基定理就可以计算出翼型的升力。

An airfoil (in American English) or aerofoil (in British English) is the shape of a wing, blade (of a propeller, rotor, or turbine), or sail (as seen in cross-section).

An airfoil-shaped body moved through a fluid produces an aerodynamic force. The component of this force perpendicular to the direction of motion is called lift. The component parallel to the direction of motion is called drag. Subsonic flight airfoils have a characteristic shape with a rounded leading edge, followed by a sharp trailing edge, often with a symmetric curvature of upper and lower surfaces. Foils of similar function designed with water as the working fluid are called hydrofoils.