What is the medical term for a blackhead?

The medical term for a blackhead is "comedone." This term specifically refers to an open comedo, which is a clogged hair follicle (pores) in the skin that is filled with oil, dead skin cells, and bacteria, leading to a characteristic dark appearance at the surface. Blackheads occur when the clogged material remains open to the air, which causes the oxidation of the melanin pigment, resulting in a dark color.

The other terms refer to different skin conditions. A pustule is a small inflamed area on the skin that is filled with pus, often associated with acne lesions. A papule is a small, raised bump on the skin that is generally solid and can occur in various skin conditions including acne. Acne vulgaris is a broader term that encompasses various forms of acne, including blackheads, whiteheads, papules, pustules, and cysts. Therefore, "comedone" is the most accurate and specific term for a blackhead.