If Uncle Bobby has a bit too much rum punch at the family Labor Day picnic and decides to roll himself up in the picnic blanket to make a human cigar, did he get “liquored up” or “liqueured up”?
Though both liquor (i.e., spirits or hard alcohol) and liqueur (aka cordials, although that’s a bit archaic) contain alcohol and are necessary ingredients in cocktails, the terms are not interchangeable. In simplest terms, liquor is not sweet, while liqueurs are.
Liquor is any unsweetened distilled alcoholic beverage — bourbon, gin, rum, tequila, vodka, whiskey, etc. — produced by distillation of grains or other plants that have gone through alcoholic fermentation. (Beer, wine, sake, and hard cider are not liquor, as they are fermented but not distilled.)
Liqueur refers to a sweetened distilled alcoholic beverage: triple sec, limoncello, amari, Chartreuse, etc. There are also cream liqueurs, which have cream added, and créme liqueurs, which are much sweeter and have a syrup-like consistency. To confuse things a bit, however, in a relatively recent phenomenon, many liquors are available in flavored forms (e.g., maple bourbon, peach whiskey, coconut rum).
Lastly, regarding poor Uncle Bobby, the proper term is “liquored up,” though if he downed the better part of a bottle of Kahlúa instead of punch, you could get away with “liqueured up.”