Any fungus of the genus Aspergillus of the Fungi Imperfecti (form-class Deuteromycetes).
Species for which the sexual phase is known are placed in the order Eurotiales. A. niger causes black mold on some foods; A. niger , A. flavus , and A. fumigatus cause aspergillosis in humans. A. oryzae is used to ferment sake , and A. wentii to process soybeans.