fetor vs mephitis

fetor and mephitis both are nouns.

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

As nouns, fetor and mephitis are synonyms defined as:

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

fetor (noun)	mephitis (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