眉是位于眼睛以上，顺着眉弓的形状而长出来的粗糙毛发。

眉毛的主要功能是防止水流入眼睛，大多是汗水和雨水。眉毛边缘弯曲的形状和眉尖所指的方向，可以确保水滴沿着脸的两旁和鼻子上流过，而不会流入眼睛里。现在人类稍微突出的眉弓也仍然在此类功能上扮演着支持的角色。和眉毛一样，眉弓也为眼睛一起屏蔽过日光。

眉毛也阻挡了头皮屑和其他微小的细屑，以防其掉入眼睛中；亦提供了一个更加敏感的感官来感觉在眼睛周围的一些东西，如小昆虫等。

眉毛在表**言沟通上亦有着一种很重要的辅助作用，可加强如惊讶或生气等情绪的表达。

The eyebrow is an area of thick, delicate hairs above the eye that follows the shape of the lower margin of the brow ridges of some mammals. Their main function is hypothesized to prevent sweat, water, and other debris from falling down into the eye socket, but they are also important to human communication and facial expression. It is not uncommon for people to modify their eyebrows by means of hair addition, removal and makeup.