The Collaborative International Dictionary of English v.0.48:
Cavalierly \Cav`a*lier"ly\, adv. In a supercilious, disdainful, or haughty manner; arrogantly. --Junius. [1913 Webster]WordNet (r) 3.0 (2006):
cavalierly adv 1: in a proud and domineering manner; "he treated his staff cavalierly" [syn: disdainfully, cavalierly]