A liqueur is a sweet alcoholic beverage, often flavoured with fruits, herbs, spices, flowers, seeds, roots, plants, barks, and sometimes cream. The word liqueur comes from the Latin word liquifacere which means "to dissolve." This refers to the dissolving of the flavourings used to make the liqueur. Liqueurs are not usually aged for long periods of time, but may have resting periods during their production to allow flavors to marry.

In some parts of the world people use the words cordial and liqueur interchangeably. Though in these places the two expressions both describe liquors made by redistilling spirits with aromatic flavorings and are usually highly sweetened, there are some differences. While liqueurs are usually flavored with herbs, cordials are generally prepared with fruit pulp or juices. Nearly all liqueurs are quite sweet, with a highly concentrated, dessert-like flavour.

Today liqueurs are made worldwide and can be enjoyed many different ways, including by themselves, poured over ice, with coffee, and mixed with cream or other mixers to create cocktails. They are often served with or as a dessert. Liqueurs may also be used in cooking.

Some liqueurs are prepared by infusing certain woods, fruits, or flowers, in either water or alcohol, and adding sugar or other items. Others are distilled from aromatic or flavouring agents. The distinction between liqueur and spirits (sometimes liquors) is not simple, especially since many spirits are available in a flavoured form today. Flavored spirits, however, are not prepared by infusion. Alcohol content is not a distinctive feature. At 15 to 30%, most liqueurs have a lower alcohol content than spirits, but some liqueurs have an alcohol content as high as 55%. Dessert wine, on the other hand, may taste like a liqueur, but contains no additional flavouring.

There are many categories of liqueurs including: fruit liqueur, cream liqueur, coffee liqueur, chocolate liqueur, schnapps liqueur, brandy liqueur, anise liqueur, nut flavoured liqueur, and herbal liqueur.