I was sitting in a hotel bar sipping cocktails with friends last night, and as one of the less well-versed of us was casting an eye over the cocktail list, he idly asked "is vermouth a liqueur?".
"Of course not", i snorted; "it's an aromatic wine.".
A look of puzzlement creased his face. "Why? What's the difference?".
"Well", i eagerly explained, "a liqueur is a base alcoholic liquid to which has been added strong flavourings, for example bitter herbs, and enough sugar to make it quite sweet. Whereas vermouth is ...".
My words tailed off into my Sazerac, and i changed the subject.
So, what is a liqueur? Why do we consider some flavoured, sweetened alcoholic liquids to be liqueurs, and not others? Why is Chartreuse a liqueur, but not vermouth? Why is Absolut Citron a vodka, but limoncello a liqueur? What about the Italian amari, like Campari, Cynar, Ramazotti, Aperol and so on?