The word prescription comes from the Latin word praescriptus.. It has the prefix pre which means before and script which means writing; so, a prescription has to be written before a drug is compounded. Historically, prescriptions were written in Latin and are still written that way today. There are two major reasons: 1  Latin is more concise than other languages.  It makes prescriptions able to be written and filled worldwide, since physicians all over the world know the Latin names for drugs and the instructions needed.