fusel oil
Noun
Meaning
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 particularly of amyl alcohol; hence, specifically applied to amyl alcohol.
Source: Webster's dictionarySynonyms
Hypernyms
Examples
It can be separated from fusel oil by either of two methods: shaking with strong brine solution and separating the oily layer from the brine layer; distilling it and collecting the fraction that boils between 125 and 140 °C.
The high molecular weight of alcohol compounds (fusel oil) is what contributes to hangovers.