any of several plants of the composite family; esp., a plant (Eupatorium perfoliatum) with flat clusters of white flowers, used in folk medicine
See boneset in American Heritage Dictionary 4
(bōnˈsĕtˌ)
noun
Any of several plants of the genus Eupatorium in the composite family, especially the eastern North American species E. perfoliatum, having opposite leaves united around the stem and clusters of small white flower heads. Also called thoroughwort.