odour vs odor

odour and odor both are nouns.

Word	Noun	Adjective	Verb	Adverb
odour	Yes	No	No	No
odor	Yes	No	No	No

As nouns, odour and odor are synonyms defined as:

Other synonyms of odour include aroma, olfactory property, scent, smell.

As nouns, odour and odor are synonyms defined as:

odour and odor: the sensation that results when olfactory receptors in the nose are stimulated by particular chemicals in gaseous form

Other synonyms of odour include olfactory perception, olfactory sensation, smell.

odour (noun)	odor (noun)
any property detected by the olfactory system	any property detected by the olfactory system
the sensation that results when olfactory receptors in the nose are stimulated by particular chemicals in gaseous form	the sensation that results when olfactory receptors in the nose are stimulated by particular chemicals in gaseous form