Dictionary

oligodendrocyte A type of cell in the central nervous system. The oligodendrocytes surround and insulate the long fibers (axons) through which the nerves send electrical messages.

oligodactyly Having fewer than the normal number of fingers or toes. Oligodactyly is the opposite of polydactyly.

oligo- Prefix meaning just a few, or scanty, as in oligodactyly (having fewer than 10 fingers or 10 toes) and oliguria (less urination than normal).

olfactory nerve The nerve that carries impulses for the sense of smell from the nose to the brain. The olfactory nerve is the first cranial nerve.

olfactory apparatus The whole system that is needed to have a sense of smell, including the nose and affiliated nerves.

olfaction The sense of smell.

olecranon The bony tip of the elbow. The olecranon is the near end of the ulna, the bone in the forearm, and it forms the pointed portion of the elbow. The triceps muscle tendon of the back of the arm attaches to the olecranon. Disease can affect the olecranon. For example, inflammation of the tiny…

ointment An oil-based preparation that is applied to the skin. Whereas an ointment has an oil base, a cream is water soluble.

Ohtahara syndrome A seizure disorder that occurs within the first month of life. Ohtahara syndrome patients may have many different types of seizures. The patient’s development is slowed, and the child can become progressively more impaired. Ohtahara syndrome is due to underdevelopment of part of the brain or to a metabolic problem. Diagnosis is made…

offspring The progeny, or young, born to a person. In a larger sense, the offspring are collectively all the descendants, the brood, or the family. For example, the offspring of someone with a genetic (inherited) condition, such as Huntington’s disease, are themselves at risk for the disease.

off-label use The practice of prescribing approved medications for conditions other than those indicated on the official medication label. In the US, the regulations of the Food and Drug Administration (FDA) permit physicians to prescribe medications for off-label use.

OD 1 Osteochondritis dissecans. 2 Overdose. 3 The right eye (oculus dexter), as opposed to OS (left eye).