Bourbon, although on the face of it a simple drink made only of corn, grains, water, yeast, oak, and time, it still has more capacity confuse than the ancient and (to some) arcane system of nomenclature used in Scotch distribution.
A Liqueur is a spirit base (whether vodka, rum, whisky, neutral grain spirit, or whatever else) flavored with natural (or unnatural?) flavorings like nuts, herbs, spices, and especially sugar. Liqueurs form the sweetener of a great many classic cocktails, and add interesting flavors to new, inventive drinks. A whisky liqueur is, simply, any sweetened or flavored spirit that starts with a whisky (or whiskey) base. Whisky liqueurs are really meant for mixing, and I doubt anyone would recommend drinking them neat at room temperature.
With or without water, this is a big drink. Something about the craggy mountain of flavor that is Booker’s was a big challenge for my nose and palate. The alcohol, although mature, is aggressive and untamed from the assault on my nose, through the river of fire on my tongue, until the tail end of the desiccating dryness of the finish.