malodorousness vs odor

malodorousness and odor both are nouns.

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

As nouns, odor is a hypernym of malodorousness; that is, odor is a word with a broader meaning than malodorousness:

Other hypernyms of malodorousness include aroma, odour, olfactory property, scent, smell.

malodorousness (noun)	odor (noun)
the attribute of having a strong offensive smell	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