rose water
A watery distillate of rose petals with a strong floral scent, used by the drop or the spoonful.
Rose water is sold in Turkish, Middle Eastern and Persian grocery shops, and often in pharmacies or the baking aisle of larger supermarkets. Its strength varies widely by origin, so start sparingly and taste, since too much quickly turns soapy.
Substitute:
There is no true substitute; orange blossom water is just as floral but tastes of citrus rather than rose, and rose syrup adds sugar as well. When in doubt, leaving it out is better than flavouring with something else.