The Collaborative International Dictionary of English v.0.48:
Magisterially \Mag`is*te"ri*al*ly\, adv. In a magisterial manner. [1913 Webster]WordNet (r) 3.0 (2006):
magisterially adv 1: in an overbearingly domineering manner; as a dictator; "this manager acts dictatorially toward his colleagues" [syn: dictatorially, autocratically, magisterially] 2: in an authoritative and magisterial manner; "she spoke authoritatively" [syn: authoritatively, magisterially]