The Collaborative International Dictionary of English v.0.48:

Bloodroot \Blood"root`\, n. (Bot.)
   A plant (Sanguinaria Canadensis), with a red root and red
   sap, and bearing a pretty, white flower in early spring; --
   called also puccoon, redroot, bloodwort, tetterwort,
   turmeric, and Indian paint. It has acrid emetic
   properties, and the rootstock is used as a stimulant
   expectorant. See Sanguinaria.
   [1913 Webster]

   Note: In England the name is given to the tormentil, once
         used as a remedy for dysentery.
         [1913 Webster]

WordNet (r) 3.0 (2006):

bloodroot
    n 1: perennial woodland native of North America having a red
         root and red sap and bearing a solitary lobed leaf and
         white flower in early spring and having acrid emetic
         properties; rootstock used as a stimulant and expectorant
         [syn: bloodroot, puccoon, redroot, tetterwort,
         Sanguinaria canadensis]