Source : Webster's Revised Unabridged Dictionary (1913)

Magisterially \Mag`is*te"ri*al*ly\, adv.
   In a magisterial manner.

Source : WordNet®

magisterially
     adv 1: in an overbearingly domineering manner; as a dictator; "this
            manager acts dictatorially toward his colleagues"
            [syn: {dictatorially}, {autocratically}]
     2: in an authoritative manner; "she spoke authoritatively"
        [syn: {authoritatively}, {with authority}]