鼻，又称鼻子，是陆上动物呼吸的器官，属呼吸系统一部份，也是哺乳类动物感应嗅觉的器官。

鼻一般在动物的头部，可能是隆起，鼻对体外的开口叫作鼻孔，鼻孔让空气进入鼻腔内，两孔气流速度不同，且每隔几小时就会交换一次。鼻有两腔，被鼻中隔隔开，哺乳类动物的鼻腔内通常长有鼻毛，作用是过滤及吸收空气中飘浮的尘埃及杂质，鼻腔壁有黏膜，有助于湿润吸入的空气，并附着杂质。鼻腔内后部则是鼻窦，位于鼻两侧的颅骨下，是感应嗅觉的神经，鼻腔连接咽喉，并与消化系统共用管道，再分支进入呼吸系统至肺部。

人类的鼻在面部的正中间。

除了动物，鼻亦可用作形容形状与鼻相近的东西，例如飞机的前端便被称为机鼻。

Anatomically, a nose is a protuberance in vertebrates that houses the nostrils, or nares, which admit and expel air for respiration in conjunction with the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next passes through the pharynx, shared with the digestive system, and then into the rest of the respiratory system. In humans, the nose is located centrally on the face and serves as an alternative respiratory passage especially during suckling for infants. On most other mammals, it is located on the upper tip of the snout.