The Collaborative International Dictionary of English v.0.48:

Quebracho \Que*bra"cho\, n. [Sp.] (Bot.)
   A Chilian apocynaceous tree (Aspidosperma Quebracho); also,
   its bark, which is used as a febrifuge, and for dyspn[oe]a of
   the lung, or bronchial diseases; -- called also white
   quebracho, to distinguish it from the red quebracho, a
   Mexican anacardiaceous tree (Loxopterygium Lorentzii) whose
   bark is said to have similar properties. --J. Smith (Dict.
   Econ. Plants).
   [1913 Webster]