What does blackhead called?

A blackhead, or open comedo is a wide opening on the skin with a blackened mass of skin debris covering the opening. Despite their name, some blackheads can be yellowish in color. A comedo is a widened hair follicle which is filled with skin debris (keratin squamae), bacteria and oil (sebum).

A closed comedo is a whitehead, while an open comedo is a blackhead. the plural of "comedo" is comedomes".