Source : Webster's Revised Unabridged Dictionary (1913)

Comfrey \Com"frey\, n. [Prob. from F. conferve, L. conferva, fr.
   confervere to boil together, in medical language, to heal,
   grow together. So called on account of its healing power, for
   which reason it was also called consolida.] (Bot.)
   A rough, hairy, perennial plant of several species, of the
   genus {Symphytum}.

   Note: A decoction of the mucilaginous root of the ``common
         comfrey'' ({S. officinale}) is used in cough mixtures,
         etc.; and the gigantic ``prickly comfrey'' ({S.
         asperrimum}) is somewhat cultivated as a forage plant.