Orange flower water
Orange flower water is a distillate of the flowers of the bitter (Seville) orange tree (Citrus aurantium). The flowers are picked and steam-distilled, then the resulting liquid is fractionated into orange flower water and the essential oil, which is called neroli and used in perfume-making. Orange flower water is typically used in Middle Eastern sweets, typically as part of a soaking syrup.
The history of orange flower water probably dates back to the 8th century Arab world, and was used to scent linens in 14th century Sicily. By the 16th century, it was being used as a flavorant, and was fairly widespread in Europe by the 17th century.
Orange flower water can be found (along with rosewater, which is made the same way) in larger supermarkets or Middle Eastern specialty stores. It is pale yellow and clear, with a sharp aroma that is green, citrus and soapy.