Bitter orange liqueur is a popular ingredient in many cocktails and recipes. However, if you're looking for a substitute or variety, there are several options available. Some of the most commonly used synonyms for bitter orange liqueur include triple sec, Cointreau, Grand Marnier, and curaçao. All of these liqueurs offer a similar citrus flavor profile to bitter orange liqueur but vary in sweetness and intensity. Depending on your recipe, you may prefer one over the other. Experimenting with different substitutes can add a unique twist to your cocktails and dishes, and broaden your flavor palate.