Masterfully \Mas"ter*ful*ly\, adv. In a masterful manner; imperiously. A lawless and rebellious man who held lands masterfully and in high contempt of the royal authority. --Macaulay.
masterfully adv 1: in a skillfully masterful manner; with the skill of a master; "the young boy played the violin sonata masterfully" 2: in a domineering and masterful manner; "his gaze held hers masterfully"