odor vs odour

odor and odour both are nouns.

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

As nouns, odor and odour are synonyms defined as:

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

As nouns, odor and odour are synonyms defined as:

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

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

odor (noun)	odour (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