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Glossary of terms

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z All 

occluded
Blocked.

occult
An injury or disease is said to be occult when it is hidden, difficult to see or unaccompanied by readily discernible signs and symptoms.

oncologic
Relating to oncology, the study of cancer and the branch of medicine devoted to the diagnosis and treatment of cancer.

oncologist
A medical doctor who specializes in oncology—the study and treatment of tumors and cancer.

oncology
The study and treatment of neoplasms (abnormal tissue growths), tumors and cancers, including their causes and development.

oophorectomy
The surgical removal of one or both ovaries.

opaque
Impervious to light or radiation; not transparent or only slightly so.

optionally retrievable filters
A device that is temporarily implanted in and then removed from the inferior vena cava, the large vein that returns blood from the legs to the heart, to prevent blood clots in the lower body from traveling to the heart or lungs.

orbit
The bony cavity containing the eyeball.

orthodontic
Related to orthodontics, a specialty within dentistry to prevent and correct teeth irregularities.

orthopaedics
The medical specialty concerned with the preservation, restoration, and development of form and function of the musculoskeletal system, extremities, spine, and associated structures by medical, surgical, and physical methods.

orthopedic cement
An acrylic cement such as polymethylmethacrylate (PMMA) used to repair bone fractures and in other orthopedic surgeries.

osmosis
Movement of a solution through the membrane of a cell.

osteoarthritis
A common condition that usually starts in middle age and is characterized by degenerative changes in the bone and cartilage of one or more joints.

osteomyelitis
Bone infection.

osteopenia
Reduction in bone mineral density to below-normal levels; the first stage of bone loss; an early-warning sign pointing to an increased risk of developing full-blown osteoporosis.

osteoporosis
A condition of reduced bone mass, with decreased outer thickness and a decrease in the number and size of the spongy structures in the bone (but normal chemical composition), resulting in increased fracture incidence. Osteoporosis is primarily classified as an age-related decline in bone mineral density. Secondary osteoporosis results from an identifiable disease (for example, diseases of the parathyroid glands, or, for instance, certain medications). See the Osteoporosis page for additional information.

ovary
One of two female reproductive glands that contain the ova, or eggs, that are released during ovulation; the fallopian tubes connect the ovaries and the uterus.

ovulation
The release of an ovum, or egg, from the ovary, which then travels through the fallopian tube to the uterus to be fertilized by a sperm