demeanor vs demeanour

demeanor and demeanour both are nouns.

Word	Noun	Adjective	Verb	Adverb
demeanor	Yes	No	No	No
demeanour	Yes	No	No	No

As nouns, demeanor and demeanour are synonyms defined as:

demeanor and demeanour: (behavioral attributes) the way a person behaves toward other people

Other synonyms of demeanor include behavior, behaviour, conduct, deportment.

demeanor (noun)	demeanour (noun)
(behavioral attributes) the way a person behaves toward other people	(behavioral attributes) the way a person behaves toward other people