Source : Webster's Revised Unabridged Dictionary (1913)

Vitriol \Vit"ri*ol\, n. [F. vitriol; cf. Pr. vitriol, vetriol,
   Sp. & Pg. vitriolo, It. vitriuolo; fr. L. vitreolus of glass,
   vitreus vitreous. See {Vitreous}.] (Chem.)
   (a) A sulphate of any one of certain metals, as copper, iron,
       zinc, cobalt. So called on account of the glassy
       appearance or luster.
   (b) Sulphuric acid; -- called also {oil of vitriol}. So
       called because first made by the distillation of green
       vitriol. See {Sulphuric acid}, under {Sulphuric}.
       [Colloq.]

   {Blue vitriol}. See under {Blue}.

   {Green vitriol}, ferrous sulphate; copperas. See under
      {Green}.

   {Oil of vitriol}, sulphuric or vitriolic acid; -- popularly
      so called because it has the consistency of oil.

   {Red vitriol}, a native sulphate of cobalt.

   {Vitriol of Mars}, ferric sulphate, a white crystalline
      substance which dissolves in water, forming a red
      solution.

   {White vitriol}, zinc sulphate, a white crystalline substance
      used in medicine and in dyeing. It is usually obtained by
      dissolving zinc in sulphuric acid, or by roasting and
      oxidizing certain zinc ores. Formerly called also {vitriol
      of zinc}.



   {Oil gas}, inflammable gas procured from oil, and used for
      lighting streets, houses, etc.

   {Oil gland}.
   (a) (Zo["o]l.) A gland which secretes oil; especially in
       birds, the large gland at the base of the tail.
   (b) (Bot.) A gland, in some plants, producing oil.

   {Oil green}, a pale yellowish green, like oil.

   {Oil of brick}, empyreumatic oil obtained by subjecting a
      brick soaked in oil to distillation at a high temperature,
      -- used by lapidaries as a vehicle for the emery by which
      stones and gems are sawn or cut. --Brande & C.

   {Oil of talc}, a nostrum made of calcined talc, and famous in
      the 17th century as a cosmetic. [Obs.] --B. Jonson.

   {Oil of vitriol} (Chem.), strong sulphuric acid; -- so called
      from its oily consistency and from its forming the
      vitriols or sulphates.

   {Oil of wine}, [OE]nanthic ether. See under {[OE]nanthic}.

   {Oil painting}.
   (a) The art of painting in oil colors.
   (b) Any kind of painting of which the pigments are originally
       ground in oil.

   {Oil palm} (Bot.), a palm tree whose fruit furnishes oil,
      esp. {El[ae]is Guineensis}. See {El[ae]is}.

   {Oil sardine} (Zo["o]l.), an East Indian herring ({Clupea
      scombrina}), valued for its oil.

   {Oil shark} (Zo["o]l.)
   (a) The liver shark.
   (b) The tope.

   {Oil still}, a still for hydrocarbons, esp. for petroleum.

   {Oil test}, a test for determining the temperature at which
      petroleum oils give off vapor which is liable to explode.
      

   {Oil tree}. (Bot.)
   (a) A plant of the genus {Ricinus} ({R. communis}), from the
       seeds of which castor oil is obtained.
   (b) An Indian tree, the mahwa. See {Mahwa}.
   (c) The oil palm.

   {To burn the midnight oil}, to study or work late at night.
      

   {Volatle oils}. See {Essential oils}, under {Essential}.

Source : WordNet®

oil of vitriol
     n : (H2SO4) a highly corrosive acid made from sulfur dioxide;
         widely used in the chemical industry [syn: {vitriol}, {sulfuric
         acid}, {sulphuric acid}]