What is a large blister containing clear, watery fluid called?

A large blister containing clear, watery fluid is specifically termed a bulla. A bulla is larger than a vesicle and is characterized by its raised, fluid-filled structure that can be found on the skin or mucous membranes. Typically, bullae measure greater than 0.5 centimeters in diameter and can be caused by various factors such as friction, burns, or certain medical conditions.

In contrast, a vesicle is similar but significantly smaller, usually less than 0.5 centimeters in diameter. A wheal refers to a raised, itchy area of skin that often appears as part of an allergic reaction; it is not a fluid-filled structure. Excoriation denotes a scratch or abrasion on the skin, which doesn’t involve the presence of a blister. Thus, bulla accurately describes the condition of a large blister containing clear, watery fluid.