Dictionary

Norwalk virus The prototype virus of the genus Norovirus. See norovirus.

North Asian tick-borne rickettsiosis See rickettsiosis, North Asian tick-borne.

norovirus One of a group of viruses that cause the “stomach flu,” or gastroenteritis. The term norovirus was approved as the official name for this group of viruses. Several other names have been used for noroviruses, including Norwalk-like viruses, caliciviruses (because they belong to the virus family Caliciviridae), and small round structured viruses. The virus…

normal range Characteristic of 95 percent of values from a normal population. The remaining normal results fall outside the normal range, as do any truly abnormal results. The normal range for a particular test result, condition, symptom, or behavior may differ, based on the patient’s age, size, sex, ethnicity, or culture.

normal pressure hydrocephalus See hydrocephalus, normal pressure.

Noonan syndrome A congenital malformation syndrome that is characterized by mildly short stature, a congenital heart defect, a broad or webbed neck, an unusual chest shape (prominent above and caved in below), low-set nipples, a characteristic facial appearance, and, in boys, testes that do not descend normally into the scrotum (cryptorchidism). Abbreviated NS. Although NS…

nonsyndromic Not part of a syndrome. Hearing loss, for instance, can be syndromic or nonsyndromic. See also syndrome.

nonsteroidal anti-inflammatory drug See NSAID.

non-small-cell lung cancer Cancer of the lung that is not small cell carcinoma. It may be bronchogenic carcinoma, squamous cell carcinoma, adenocarcinoma, or large cell carcinoma of the lung. The distinction between small and non-small-cell lung cancers is made under the microscope. Knowing which type a patient has is important for proper therapy. The treatment…

nonseminoma A type of testicular cancer that arises in specialized sex cells called germ cells that give rise to sperm. Nonseminomas include embryonal carcinoma, teratoma, choriocarcinoma, and yolk sac tumor.

non-rapid eye movement sleep See NREM sleep.

nonpathogenic Incapable of causing disease. For example, nonpathogenic E. coli are E. coli bacteria that do not cause disease, but instead live naturally in the large intestine.