mephitis vs malodour

mephitis and malodour both are nouns.

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

As nouns, mephitis and malodour are synonyms defined as:

mephitis and malodour: a distinctive odor that is offensively unpleasant

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

mephitis (noun)	malodour (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