Definitions for "Fusel oil"
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;
amyl alcohol or a mixture of amyl alcohols.
a mixture of amyl alcohols and propanol and butanol formed from distillation of fermented liquors