The Collaborative International Dictionary of English v.0.48:

Turbeth \Tur"beth\ (t[^u]r"b[e^]th), n.
   See Turpeth.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Turpeth \Tur"peth\, n. [NL. turpethum, fr. Per. tirbid a
   cathartic, turbad a purgative root. Cf. Turbith.] [Written
   also turbeth, and turbith.]
   1. (Bot.) The root of Ipom[oe]a Turpethum, a plant of
      Ceylon, Malabar, and Australia, formerly used in medicine
      as a purgative; -- sometimes called vegetable turpeth.
      [1913 Webster]

   2. (Chem.) A heavy yellow powder, Hg3O2SO4, which consists
      of a basic mercuric sulphate; -- called also turpeth
      mineral.
      [1913 Webster]