Naph"tha (?), n. [L. naphtha, Gr. &?;&?;&?;&?;&?;, fr.Ar. nafth, nifth.] 1. (Chem.) The complex mixture of volatile, liquid, inflammable hydrocarbons, occurring naturally, and usually called crude petroleum, mineral oil, or rock oil. Specifically: That portion of the distillate obtained in the refinement of petroleum which is intermediate between the lighter gasoline and the heavier benzine, and has a specific gravity of about 0.7, -- used as a solvent for varnishes, as a carburetant, illuminant, etc.

2. (Chem.) One of several volatile inflammable liquids obtained by the distillation of certain carbonaceous materials and resembling the naphtha from petroleum; as, Boghead naphtha, from Boghead coal (obtained at Boghead, Scotland); crude naphtha, or light oil, from coal tar; wood naphtha, from wood, etc.

&fist; This term was applied by the earlier chemical writers to a number of volatile, strong smelling, inflammable liquids, chiefly belonging to the ethers, as the sulphate, nitrate, or acetate of ethyl. Watts.

• (historic) naturally-occuring liquid petroleum
  
• a flammable liquid distilled from petroleum or coal tar, especially as used in solvents or petrol
       *1995: The Common Room and the Library were lit by anbaric light, but the Scholars preferred the older, softer naphtha lamps in the Retiring Room. — Philip Pullman, Northern Lights