smell

The structure of the nose. The organs of smell are confined to a small area in the roof of the nasal cavity. The olfactory cells are stimulated when certain molecules reach them. Smell is one of our most subtle senses: tens of thousands of smells can be distinguished. By comparison, taste, although closely related to smell, is a crude sensation. All the subtleties of taste depend upon smell.

Sense that responds to certain molecules in the air. It works by having receptors for particular chemical groups, into which the airborne chemicals must fit to trigger a message to the brain.

A sense of smell is used to detect food and to communicate with other animals (see pheromone and scent gland). Humans can distinguish between about 10,000 different smells. Aquatic animals can sense chemicals in water, but whether this sense should be described as ‘smell’ or ‘taste’ is debatable. See also nose.