Triple sec
Triple sec is an orange-flavoured liqueur that originated in France. It usually contains 20–40% alcohol by volume. Triple sec is rarely consumed neat, but is used in preparing many mixed drinks such as margaritas, cosmopolitans, sidecars, Long Island iced teas, and mai tais. The origin of the name "triple sec" is disputed. The term is French and composed of triple, with the same meaning as in English, and sec, the French word for "dry". Some sources claim it comes from a triple distillation process used to create the liqueur, but others say that a triple distillation is not used. Cointreau, a brand of triple sec, is reported to have invented the term based on the three types of orange peels used in the liqueur, although other reports have Cointreau claim the triple to mean "three times the flavour of Curaçaos."
Source: Wikipedia