Source : Webster's Revised Unabridged Dictionary (1913)

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 : WordNet®

Caulophyllum thalictroides
     n : tall herb of eastern North America and Asia having blue
         berrylike fruit and a thick knotty rootstock formerly
         used medicinally [syn: {blue cohosh}, {blueberry root}, {papooseroot},
          {papoose root}, {squawroot}, {squaw root}, {Caulophyllum
         thalictrioides}]