In pharmacy what does the symbol Rx mean?

Before products became available as ready made the physician on his prescription pad would write the list of ingredients and their quantity to be made. This was known as a recipe or known as an RX.

This symbol originated in medieval manuscripts as an abbreviation of the Late Latin verb recipe, the imperative form of recipere, "to take" or "take thus".Literally, the Latin word recipe means simply "Take...." and medieval prescriptions invariably began with the command to "take" certain materials and compound them in specified ways.