While good answers have been provided here, I would like to add.
In my studies I have found several references to "Orange Blossum Water" being essential to several gardening procedures, specifically the ancient Myrrh gardens of early Eastern Africa, and later, Syria. Myrrh is notoriously difficult to grow, and it is true that the entire time these gardens were in operation, they were in a constant and slow decline in the number of plants maintained, although the one in Syria lasted for several hundred years before it was discontinued altogether. (circa 700-1200A.D. - I am positive many other gardens have existed)
In their manuscr*ipts, the caretakers denoted that the Myrrh gardens absolutely *required* the water of a natural spring around which an orchard of oranges grew. The roots of the orange blossum trees infused the spring water with the essence of orange, and this was sustaining to the Myrrh.
Just something I read while studying Medicines of the Old World in college. Thought it would add to the discussion as it is an entirely different term from the accurate recipe posted above.