What is the term for a small blister or sac containing clear fluid beneath the epidermis?

The term that describes a small blister or sac containing clear fluid beneath the epidermis is a vesicle. Vesicles are typically small, well-defined, and filled with a serous fluid, which separates them from the surrounding tissue. They often arise in response to irritation, infection, or allergies, and understanding their characteristics can assist in proper diagnosis and treatment in the field of dermatology or within a manicuring context where skin health is vital.

The other terms refer to different skin conditions: a wheal is raised and often itchy, crust refers to a dried exudate on the skin's surface, and a fissure denotes a crack or split in the skin. In this case, recognizing the specific nature of a vesicle is crucial for effective communication and care in beauty and health-related practices.