Smell is one of your five senses—the one you use your nose for. Dogs have such a sharp sense of smell that they can sniff out things like explosives and drugs.
Your sense of smell gives you important information, like "this milk is sour," or "I need a shower." An individual odor or scent is also a smell, and to perceive it with your nose is to smell it. If someone says, "You smell," it's not a compliment—what they mean is, "You don't smell good." While experts believe that smell has an Old English root, it was never recorded.