Dictionary

onycho- Prefix having to do with the nails, as in onychodystrophy (abnormal growth and development of nails).

oneirophrenia A hallucinatory (dream-like) state that is caused by such conditions as prolonged sleep deprivation, sensory isolation, and drug use.

oneiric Relating to dreams, dream-like. From the Greek oneiros, meaning “dream.”

Ondine’s curse Failure of the central nervous system to control breathing while a person is asleep. People with Ondine’s curse usually have no problem breathing while awake. With Ondine’s curse, the voluntary control of ventilation that operates during waking hours is generally intact, but the involuntary (autonomic) control of respiration is impaired. Also known as…

oncology The field of medicine that is devoted to cancer. Clinical oncology consists of three primary disciplines: medical oncology (the treatment of cancer with medicine, including chemotherapy), surgical oncology (the surgical aspects of cancer including biopsy, staging, and surgical resection of tumors), and radiation oncology (the treatment of cancer with therapeutic radiation).

oncologist A physician who specializes in the diagnosis and treatment of cancer. After a cancer diagnosis is made, it is the oncologist’s role to explain the cancer diagnosis and the meaning of the disease stage to the patient; discuss various treatment options; recommend the best course of treatment; deliver optimal care; and improve quality of…

oncogene A gene that contributes to the transformation of normal cells into cancerous cells. Many oncogenes are genes that had a normal role in the cell (proto-oncogenes) and were altered by mutation to become oncogenes. See also proto-oncogene.

onchocerciasis See river blindness.

omphalomesenteric duct A narrow tube that is present in the early embryo that connects the midgut of the embryo to the yolk sac outside the embryo through the umbilical opening. Later in development, it is usually obliterated, but a remnant of it may persist, most commonly as a finger-like protrusion from the small intestine that…

omphalocele A birth defect in which part of the intestine, covered only by a thin transparent membrane, protrudes outside the abdomen at the umbilicus. An omphalocele occurs due to a failure during embryonic development for a section of the intestines (the midgut) to return from outside the abdomen and reenter the abdomen as it should….

omphalo- Prefix indicating a relationship to the umbilicus (the navel). From the Greek word for the decorative boss protruding from the center of a Greek warrior’s shield.

Ommaya reservoir A device that is implanted under the scalp to deliver anticancer drugs to the fluid surrounding the brain and spinal cord.