STAPHYLOCOCCUS

n. type of spherical bacteria

Staphylococcus (in Greek staphyle means bunch of grapes and coccos means granule) is a genus of Gram-positive bacteria. Under the microscope they appear round (cocci), and form in grape-like clusters.The Staphylococcus genus includes thirty-one species. Most are completely harmless, and reside normally on the skin and mucous membranes of humans and other organisms. Found worldwide, they are a small component of soil microbial flora.
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Staphylococcus /Staph·y·lo·coc·cus/ a genus of gram-positive bacteria that are potential pathogens, causing local lesions and serious opportunistic [more]Staphylococcus - Community and Resources

Noun
1. spherical gram-positive parasitic bacteria that tend to form irregular colonies; some cause boils or septicemia or infections
(synonym) staphylococci, staph
(hypernym) coccus, cocci
(member-holonym) genus Staphylococcus

(and do) cause a multitude of diseases. The name comes from the Greek staphyle meaning a bunch of grapes + kokkos meaning berry, and that is exactly what Staph look like under the microscope, like a bunch of grape or little round berries. (In technical terms, these are gram-positive, facultative anaerobic, usually unencapsulated cocci). Staph can cause illness directly by infection or indirectly through products they make such as toxins responsible for food poisoning and toxic shock syndrome.