翅膀亦称翼，为鸟与昆虫等动物用来飞行的器官。在现代，许多机械对象也会使用翅膀飞翔，例如航天飞机及飞机等。

鸟的翅膀是其飞翔的主要结构，翅膀外面覆盖硬羽，其特性适于飞行。翅膀的形状由羽毛决定，使鸟能够飞行。羽毛上下拍动可以形成推动力（或阻力）以飞行。不同的鸟有着不同的翅膀类型，飞行速度高的鸟类翅膀类型一般为半月形，飞行空间较小的鸟翅膀一般有小的空隙以减轻重量。

A wing is a type of fin with a surface that produces aerodynamic forces facilitating movement through air and other gases, or water and other liquids. As such, wings have an airfoil shape, a streamlined cross-sectional shape producing lift.

The word "wing" from the Old Norse vængr for many centuries referred mainly to the foremost limbs of birds (in addition to the architectural aisle.) But in recent centuries the word's meaning has extended to include lift producing appendages of insects, bats, pterosaurs, boomerangs, some sail boats and aircraft, or the inverted airfoil on a race car that generates a downward force to increase traction.