An odor or odour is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and many animals can perceive via their sense of smell. An odor is also called a "smell" or a "scent", which can refer to either an unpleasant or a pleasant odor.
"Smell", from Allegory of the Senses by Jan Brueghel the Elder, Museo del Prado
Odor control covers at a sewage treatment plant: Under these covers, grit and gravel are settled out of the wastewater.
A sense is a biological system used by an organism for sensation, the process of gathering information about the surroundings through the detection of stimuli. Although, in some cultures, five human senses were traditionally identified as such, many more are now recognized. Senses used by non-human organisms are even greater in variety and number. During sensation, sense organs collect various stimuli for transduction, meaning transformation into a form that can be understood by the brain. Sensation and perception are fundamental to nearly every aspect of an organism's cognition, behavior and thought.
Philippe Mercier - The Sense of Taste - Google Art Project
The sense of smell. Bequest of Mrs E.G. Elgar, 1945 Museum of New Zealand Te Papa Tongarewa.
Lairesse's Allegory of the Five Senses
Detail of The Senses of Hearing, Touch and Taste, Jan Brueghel the Elder, 1618
