Glossary try the best to avoid the use of medical terms that could make it more difficult to understand the information on this website. Still, there are a number of terms that can't be avoided and that are useful to know because they are so often used by the doctors, nurses, and other medical professionals with whom you might speak. The list below includes the terms used on for which we have provided definitions.

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Term Definition

A group of chemicals derived from cholesterol that typically functions as hormones; common types of steroids include sex steroids (estrogen, progesterone, testosterone), glucocorticosteroids (cortisol, prednisone, dexmethasone), and mineralacorticosteroids (aldosterone).


A narrowing or constriction of a passageway in the body, such as in a blood vessel or spinal canal

Stem cells

Cells that are able to develop into many (or all) types of cells


A group of drugs that reduce the production of cholesterol and promote the clearance of low-density lipoprotein (LDL) from the blood by the liver.

  • In medicine, a defined period or phase in the development, progress or extent of a disease or condition; the process of determining the period or phase of a disease or condition. In cancer, the stage is the degree to which the cancer has grown or spread. Generally, lower numbers and/or letters mean less extensive stages.
  • (On a microscope) a raised and usually movable plate on which a slide or object is placed for examination.
  • A raised floor or platform.

Viscous material that is derived from the lower air passages such as the lungs and bronchi that may contain substances such as mucus, blood, pus and/or bacteria; it is not the saliva that is produced by the glands in the mouth.


1. Small, usually single-celled reproductive unit of some microorganisms such as fungi.
2. Form assumed by some bacteria that is resistant to heat, drying, and chemicals; an example of a disease caused by spore-forming bacteria is anthrax.


An inflammation of the vertebrae


organ located in the abdomen that functions mainly to store blood cells, remove old blood cells from circulation, produce lymphocytes to fight infection, and filter foreign substances from the blood


Any of a group of spiral-shaped bacteria

Spina bifida

A birth defect in which the bones of the spine do not close around the spinal cord (the continuation of brain tissue that normally is surrounded by the spinal bones); this opening may be covered by skin (also called spina bifida occulta, which means hidden), in which case there may be no or mild symptoms. In other cases, the skin does not cover the defect, allowing the covering of the brain and spinal cord, the meninges, to protrude out through the skin (meningocele) or, in some cases, to rupture, exposing the spinal cord itself (meningomyelocyle). These latter two examples may cause severe damage to the nerves of the legs and lower abdomen, causing paralysis and bowel and bladder malfunction.


In the clinical laboratory:
1. a test's ability to correctly exclude individuals who do not have the given disease or disorder;
2. a test's ability to correctly detect or measure only the substance of interest and exclude other substances

Somatic Cells

All body cells, except the reproductive cells


Evidence of a disease or condition perceived by a physician or person other than the patient


Examination of the rectum and lower colon with a rigid or flexible lighted instrument