1. Pertaining to the acquisition of a disease in a hospital or other health facility; used especially in reference to hospital-acquired infections and diseases: Every once in a while, as a nurse, Freda has acquired some nosocomial illnesses; such as, MRSA or "Methicillin-resistant Staphylococcus aureus", which is a kind of bacteria that has shown resistance to Methicillin, that is a very strong antibiotic.

Since antibiotics are used so often, there are bacteria that are resistant to them and which have also become common in medical centers where there are many nosocomial contagions.

2. Something that takes place in a medical institution; such as, a description of an infection not present or incubating prior to a patient’s admittance, but generally occurring 72 hours after he or she arrived there: Nosocomial refers to a secondary disorder associated with hospitalization but which is unrelated to the primary illness of the sick person.

The term usually refers to diseases invalids keep getting; however, some general clinic personnel are also acquiring nosocomial viruses, too.