Odor

An odor or odour is a volatilized chemical compound, usually at a very low concentration, which humans and other animals perceive by the sense of olfaction.

Odors are also called smells, which can be used to describe both pleasant and unpleasant odors. The words fragrance, scent, or aroma are used mostly by the food and cosmetic industry to describe a pleasant odor, and is sometimes used to refer to perfumes. On the other hand, the words stench, reek, and stink are used specifically to describe unpleasant odors.