ribwort vs buckthorn

ribwort and buckthorn both are nouns.

Word	Noun	Adjective	Verb	Adverb
ribwort	Yes	No	No	No
buckthorn	Yes	No	No	No

As nouns, ribwort and buckthorn are synonyms defined as:

ribwort and buckthorn: an Old World plantain with long narrow ribbed leaves widely established in temperate regions

ribwort (noun)	buckthorn (noun)
an Old World plantain with long narrow ribbed leaves widely established in temperate regions	any shrub or small tree of the genus Bumelia
	a shrub or shrubby tree of the genus Rhamnus; fruits are source of yellow dyes or pigments
	an Old World plantain with long narrow ribbed leaves widely established in temperate regions