What term describes a large blister that contains watery fluid?

The term that describes a large blister containing watery fluid is "bulla." In dermatological terminology, a bulla is greater than 0.5 cm in diameter and is filled with serous fluid, which can occur in various conditions such as burns, insect bites, or certain skin diseases. It is important to recognize a bulla as it indicates a more significant area of fluid accumulation compared to smaller blisters.

In contrast, a vesicle refers to a smaller blister, usually less than 0.5 cm in size and often also containing serous fluid. An eruption describes the general appearance of a skin lesion or rash, rather than a specific type of blister. A pustule, on the other hand, is a small elevation of the skin that is filled with pus, indicating a potential infection or inflammation.

Each term serves a specific purpose in medical terminology, helping healthcare professionals describe various skin conditions accurately. Understanding these distinctions is crucial for effective communication and diagnosis in the medical field.