The empire was referred to variously as universum regnum ("the whole kingdom", as opposed to the regional kingdoms), Romanorum sive Francorum imperium ("empire of the Romans and Franks"), Romanum imperium ("Roman empire") or even imperium christianum ("Christian empire").
Imperiet blev omtalt under forskellige navne som universum regnum ("hele kongeriget", modsat de regionale kongeriger), Romanorum sive Francorum imperium ("Romerne og frankernes imperium"), Romanum imperium ("Romernes imperium") eller sågar imperium christianum ("det kristne imperium").