O

Obesity
Pronounced – oh-BEE-si-tee
Obesity is excess body fat. Obesity is a range of weight that is greater than what is generally considered healthy for a given height. The term also identifies ranges of weight that have been shown to increase the likelihood of certain diseases and other health problems.

Obstruction
Pronounced – ub-STRUK-shun
A blockage in the gastrointestinal (GI) tract that prevents the flow of liquids or solids.

Oligodendrocyte
The cells that make and maintain myelin in the central nervous system.

Optic Neuritis
An inflammatory disorder of the optic nerve that usually occurs in only one eye and causes visual loss and sometimes blindness. It is generally temporary.

Origin
The beginning of existence of something.

Oropharynx
The area of the throat that is at the back of the mouth. The oropharynx is in contrast to the nasopharynx, the part of the throat that lies behind the nose.

Ostomy
Pronounced – AH-stuh-mee
An operation that makes it possible for stool to leave the body through an opening made in the abdomen. An ostomy is necessary when part or all of the intestines are removed. Colostomy and ileostomy are types of ostomy.

Otolaryngologist
Pronounced – oh-toe-lair-in-goll-oh-jest
Doctors trained in the medical and surgical management and treatment of patients with diseases and disorders of the ear, nose, throat (ENT), and related structures of the head and neck. They are commonly referred to as ENT physicians.

Over-the-Counter (OTC)
Pronounced – oh-ver thuh kown-ter
Medicines you can buy at a pharmacy or on store shelves without a doctor’s prescription, such as cold medicine, medicines for stomach pain, or pain relievers. A few examples – aspirin, advil (pain reliever), aleve (pain reliever), ibuprofen (pain reliever), antacids (heartburn, gas, indigestion), Monistat (treats yeast infections), laxatives (for constipation), sleep aids.

Overweight
Overweight means weighing too much. Overweight is defined as a body mass index (BMI) of 25 to 29.9. Body weight comes from fat, muscle, bone, and body water. Although BMI correlates with the amount of body fat, BMI does not directly measure body fat. Some people, such as athletes, may have a BMI that identifies them as overweight even though they do not have excess body fat.