An unscrupulous business that sells "degrees" with cursory or no course work required. The diplomas, degrees, and other papers sold are easily recognized by legitimate academic institutions and employers as valueless and fraudulent. Diploma mills are often fly-by-night schemes operated from a post office box; they escape prosecution by vanishing and, perhaps, starting again under a new name.
an institution of higher education that operates without supervision from a state or professional agency and grants diplomas that are fraudulent or, because of the lack of proper standards, considered worthless
an unaccredited school (or a business claiming to be a school) that awards a degree without requiring classwork meeting college-level standards