Source : Webster's Revised Unabridged Dictionary (1913)

Imperially \Im*pe"ri*al*ly\, adv.
   In an imperial manner.

Imperially \Im*pe"ri*al*ly\, n.
   Imperial power. [R.] --Sheldon.

Source : WordNet®

imperially
     adv : in an imperial manner; "imperially decreed"