With brazen disregard for the sign that said "No Cellphones," the woman took a long call in the dentist's waiting room, irritating the other patients. Brazen describes something shocking or done shamelessly.
The Middle English word was brasen, "made of brass," from Old English bræs, "brass." In its literal sense, this word can mean "made of or resembling brass," as in a brazen drinking cup from a medieval castle. It can also mean overly or disrespectfully bold. A near synonym of brazen is our English word brassy, which has the additional meaning of being loud and showy.