Cohosh \Co"hosh\, n. (Bot.) A perennial American herb (Caulophyllum thalictroides), whose rootstock is used in medicine; -- also called pappoose root. The name is sometimes also given to the Cimicifuga racemosa, and to two species of Act[ae]a, plants of the Crowfoot family.

Source: Webster's Revised Unabridged Dictionary (1913)