The document defines a liqueur as a sweetened and flavored spirituous liquor. Liqueurs typically contain 30-65% alcohol and have three main elements - a spirit base like brandy or rum, flavoring agents, and a sweetener. Some common liqueurs mentioned include Advocaat, Benedictine, Calvados, Cointreau, Creme de Cacao, Izarra, Kahlua, Tia Maria, Slivovitz, and Malibu. Liqueurs are used in cooking, cocktails, and traditionally served neat in small glasses before or after meals.