stinking horehound vs fetid horehound

stinking horehound and fetid horehound both are nouns.

Word	Noun	Adjective	Verb	Adverb
stinking horehound	Yes	No	No	No
fetid horehound	Yes	No	No	No

As nouns, stinking horehound and fetid horehound are synonyms defined as:

stinking horehound and fetid horehound: ill-smelling European herb with rugose leaves and whorls of dark purple flowers

Other synonyms of stinking horehound include Ballota nigra, black archangel, black horehound.

stinking horehound (noun)	fetid horehound (noun)
ill-smelling European herb with rugose leaves and whorls of dark purple flowers	ill-smelling European herb with rugose leaves and whorls of dark purple flowers