Which term describes a small blister-like elevation on the skin?

The term that describes a small blister-like elevation on the skin is "vesicle." Vesicles are filled with fluid and are typically small, measuring less than 1 centimeter in diameter. They can occur due to various conditions, such as infections, allergic reactions, or skin irritations. Their primary characteristic is that they are raised above the surface of the skin and contain a clear or serous fluid, which distinguishes them from other skin lesions.

In contrast, a "wheal" refers to a raised, itchy area of skin that can occur in allergic reactions, often associated with conditions like hives. A "zygote" is an early developmental stage of an organism formed by the union of a sperm and egg, and does not relate to skin conditions. Finally, "villus" refers to small, finger-like projections found in the intestine that increase surface area for absorption, unrelated to the skin or blister formations. Therefore, "vesicle" is the precise term used in dermatology to describe the specific type of skin elevation mentioned in the question.