An oily, acid, poisonous liquid occurring in imperfectly distilled alcoholic products and consisting chiefly of amyl alcohols.

It is a mixture of high-molecular weight alcohols containing also esters and fatty acids, sometimes formed as a toxic impurity in the distillation products of alcoholic fermentation. Small amounts contribute to the characteristic flavor of a whiskey.

It is used as a source of higher alcohols and in making paints and plastics.