a downy perennial herbaceous Old World plant, Marrubium vulgare, with small white flowers that contain a bitter juice formerly used as a cough medicine and flavouring: family Lamiaceae (labiates)
See also black horehound
2. water horehound
Word origin
Old English hārhūne, from hār grey + hūne horehound, of obscure origin
horehound in American English
(ˈhɔrˌhaʊnd)
noun
1.
a bitter herb (Marrubium vulgare) of the mint family, with white, downy leaves
2.
a bitter juice extracted from its leaves, stem, or flowers and used in medicines and confections
3.
cough medicine or candy made with this juice
4.
any of various other mints
Word origin
ME horehune < OE harhune < har, white, hoar + hune, horehound