This is also the root of other English words like:
* Dictate: To speak or read something aloud to be written down.
* Dictation: The act of dictating.
* Dictionary: A book containing words and their meanings.
* Predict: To say what will happen in the future.
* Indict: To formally accuse someone of a crime.
So, an edict is essentially a "spoken" or "pronounced" order or decree, often issued by someone in authority.