Dictionary of Medical Terms

Gain a better understanding of medical terminology by searching our dictionary of more than 1,300 terms.

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ADH

Antidiuretic hormone. One of the hormones produced by the pituitary gland. A shortage of this hormone causes increased loss of…
adhesion

The sticking of one surface to another. This can occur when scar tissue causes organs or loops of intestine to…
adipose fatty cells

Special cells in which fat is stored when a person’s caloric intake is greater than that required by one’s…
adrenal glands

Located on top of the kidneys, these glands produce hormones helpful in regulating the body’s metabolism.
adrenaline

Epinephrine. One of several hormones produced by the adrenal glands.
aerobic

Requiring the use of oxygen. Exercise that conditions the heart and lungs by increasing the efficiency of oxygen intake by…
afterbirth

The placenta, which is attached to the fetus by the umbilical cord and must be delivered after the baby.
AIDS

Acquired immunodeficiency syndrome. A disease of the immune system caused by the HIV virus.
airway

The passage by which air enters and exits the lungs.
albinism

The absence of all normal body pigmentation at birth, a condition that can occur in all races.
albino

A person with albinism.
albumin

A water-soluble protein found in milk, egg, muscle, blood and many vegetable tissues and fluids.
aldosteronism

A condition resulting when the adrenal glands produce too much of the hormone aldosterone, which regulates fluids and salt in…
alimentary

Having to do with food or nutrition. The alimentary tract is the digestive tract.
allergen

A substance capable of producing an allergic reaction.
allergy

An exaggerated immune response to substances in the environment.
alopecia

Hair loss, especially of the head.
alpha1-antitrypsin deficiency

Congenital lack of an enzyme that leads to cirrhosis of the liver and obstructive lung disease.
altitude sickness

A potentially fatal illness caused by being at altitudes high enough to reduce the amount of oxygen available to the…
alveoli

The sacs in the lungs at the ends of the smallest airways where oxygen is exchanged for carbon dioxide in…
amblyopia

Impaired vision without an apparent cause.