Elockan was the official name of the Elosian Empire. The relationship of the word to the name of the city of Elos and the Elos River is uncertain. It is an archaic word that has no clear meaning in modern standard Elosian, or even the standard language of the late empire.
At the time that the empire was first established (-393EYE), the language spoken between member cities of the League of Enat was not the dialect of the city of Elos (from which the modern language derives), but some other related but now extinct dialect. Elockan was probably coined in that forgotten language, not in what became what we know as Elosian.