1) visbreaker 2) viscosity breaker a device for reducing the viscosity and lowering the pour point of distillation residues or, if required, of gas oil, derived from paraffinic crudes, achieved by the destructive cracking of paraffinic hydrocarbons without the aid of catalysts GRM: n. (1,2) Note: in the fractionating section of a visbreaker the soaker effluents are separated into the following fractions: gas (butane and lighter), gasoline, kerosine, gas oil and visbroken residue