Dictionary:

aspergillus

  (ăs'pər-jĭl'əs)

Any of various fungi of the genus Aspergillus, which includes many common molds.

[New Latin Aspergillus, genus name, from aspergillum, aspergillum (from its resemblance to an aspergillum brush). See aspergillum.]

A genus of fungi (molds), several species of which are parasitic and opportunistic pathogens. Others produce toxins and when they contaminate animal feeds they can cause heavy losses. Includes A. amstelodami, A. chevalieri, A. clavatus, A. flavus oryzae, A. fumigatus, A. maydis, A. niger, A. ochraceus, A. parasiticus, A. taumanii, A. wentii.

• A. fumigatus — a cause of respiratory tract disease in many species. See airsacculitis, aspergillosis.
• A. nidulans, A. versicolor — produce known carcinogenic toxin, sterigmatocystin.
• A. terreus — a cause of fescue foot and the most common cause of canine disseminated aspergillosis.

The noun has one meaning:

Meaning #1: genus of common molds causing food spoilage and some pathogenic to plants and animals
  Synonym: genus Aspergillus