n. [ NL. turpethum, fr. Per. tirbid a cathartic, turbad a purgative root. Cf. Turbith. ] [ Written also turbeth, and turbith. ] 1. (Bot.) The root of Ipomœa 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 ]