How is a bulla defined?

A bulla is specifically defined as a large blister that is filled with watery fluid. This term is used in dermatology to describe a raised area on the skin that is larger than 0.5 centimeters in diameter and can be caused by various factors, including friction, burns, or certain skin conditions. The presence of the fluid inside distinguishes it from other skin lesions, such as vesicles, which are smaller blisters. Understanding this definition is crucial for recognizing different types of skin lesions and their implications in skin health and treatment options.