反曲弓是一种侧面看来与普通长弓不同的弓：一把未上弓弦的反曲弓弓臂末端向外弯曲。其中一个专门的定义指出，反曲弓与其他弓的分别在于上弦的反曲弓的弓弦与其弓臂有所接触。相比同等拥有直臂的弓，反曲弓可保存更多能量，使得射出的箭有更高的动能。因此，反曲弓可以比普通的弓造得更短，却可保持其威力。这个优势使得反曲弓适合用于较长兵器会构成不便的地方，例如丛林、森林或马背上。相对而言，传统较直身的长弓会引起「层递」的效应——即弓拉得愈开，拉弓所需的力会增加得非常显著。

反曲的弓臂会使弓承受更大的拉力，而且射出箭时会产生更大的噪音。若反曲的程度过甚，会使弓上弦后变得不稳定。由于未上弦的反曲弓的形状对于较少接触的人容易引起混淆，很多美国土着的弓曾被外国人反向上弦，并引致发射时弓损毁。

A recurve bow is a bow with limbs that curve away from the archer when unstrung. A recurve bow stores more energy and delivers energy more efficiently than the equivalent straight-limbed bow, giving a greater amount of energy and speed to the arrow. A recurve will permit a shorter bow than the simple straight limb bow for a given arrow energy and this form was often preferred by archers in environments where long weapons could be cumbersome, such as in brush and forest terrain, or while on horseback.