mephitis vs malodor

mephitis and malodor both are nouns.

Word	Noun	Adjective	Verb	Adverb
mephitis	Yes	No	No	No
malodor	Yes	No	No	No

As nouns, mephitis and malodor are synonyms defined as:

Other synonyms of mephitis include fetor, foetor, malodour, reek, stench, stink.

mephitis (noun)	malodor (noun)
a distinctive odor that is offensively unpleasant	a distinctive odor that is offensively unpleasant
a poisonous or foul smelling gas emitted from the earth