What is the primary defining characteristic of a liqueur?

A liqueur is primarily defined by its sweetness and the complex flavors derived from various ingredients. The key characteristics of liqueurs include a base of distilled spirits that is often sweetened with sugar or other sweeteners, and then flavored with an array of ingredients such as fruits, herbs, spices, or nuts. This combination of sweetness and flavoring distinguishes liqueurs from other spirits that may not have these qualities.

Many spirits may be distilled, but the defining characteristic of a liqueur is not simply that it is distilled; rather, it is how that distilled base is treated with sweetness and flavoring. While some liqueurs have a significantly high alcohol by volume (ABV), this is not a defining trait, as there are many spirits that also have high ABV but are not classified as liqueurs. Unsweetened products would not qualify as liqueurs either, as absence of sweetness significantly deviates from the core identity of this category.