Source : Webster's Revised Unabridged Dictionary (1913)

Imperium \Im*pe"ri*um\, n.; pl. {Imperia}. [L. See {Empire}.]
   1. Supreme power; absolute dominion; empire.

   2. (Law) The right to command, which includes the right to
      employ the force of the state to enforce the laws. It is
      one of the principal attributes of the executive power.

Source : WordNet®

imperia
     See {imperium}