fusel oil

n., . [ G. fusel bad liquor. ] (Chem.) A hot, acrid, oily liquid, accompanying many alcoholic liquors (as potato whisky, corn whisky, etc.), as an undesirable ingredient, and consisting of several of the higher alcohols and compound ethers, but mostly of amyl alcohol; hence, amyl alcohol or a mixture of amyl alcohols. [ 1913 Webster +PJC ]