Dictionary

Enter a word or phrase below to search our online dictionary of over 1,300 general medical terms, or click on a letter of the alphabet to view all terms beginning with that letter:

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Phrase Definition
abdomen The part of the body between the chest and pelvis.
abortion 1. Induced abortion is a procedure done to end pregnancy. 2. Spontaneous abortion is a naturally occurring abortion (also called miscarriage). 3. Therapeutic abortion is an induced abortion required to save the life or health of the mother.
abrasion A wound caused by scraping the skin. A "skinned knee" is a common example.
abscess A swollen, inflamed area where pus gathers.
absorption To take in substances through the skin or mucous membranes.
abstinence To hold back or restrain. For example, to refrain from the use of drugs or alcohol, or from having sexual intercourse.
acclimation The process of getting used to a new climate or altitude.
Achilles' tendon The strong tendon at the back of the ankle that attaches the calf muscle to the heel.
acidosis An abnormal condition in the body in which excessive acid lowers the pH of the blood and body tissues.
acne A skin disorder usually found in adolescents and young adults.
acoustic Having to do with sound and hearing.
acromegaly A condition that occurs when the pituitary gland produces too much growth hormone. In adults, this can cause overgrowth of bones that occurs in smaller bones, such as those in the jaw, hands and feet. In children or teenagers, this can cause giantism.
actinic keratoses Scaly, pink, gray or tan patches or bumps on the face or scalp, or on the back of the hands. Occur mostly on people who have light skin that has been damaged by the sun.
acupuncture An ancient Chinese method to relieve pain or treat disease by inserting needles into various parts of the body.
acute 1. Of short course. 2. Severe, but of a short duration. Not chronic.
addiction Strong dependence or habitual use of a substance or practice, despite the negative consequences of its use.
Addison's disease An ailment characterized by underfunctioning of the adrenal glands. Characterized by anemia, weakness, low blood pressure and brownish discoloration of the skin.
adenitis Swelling of a gland.
adenoids Glandular tissue in the back of the throat that may swell, especially during childhood, obstruct breathing and speaking, and lead to ear infections.
adenoma A noncancerous tumor of glandular tissue.
adenovirus One of the viruses that cause the common cold.
ADH Antidiuretic hormone. One of the hormones produced by the pituitary gland. A shortage of this hormone causes increased loss of body fluids through the kidneys.
adhesion The sticking of one surface to another. This can occur when scar tissue causes organs or loops of intestine to stick together. Occasionally, these adhesions may produce an intestinal obstruction or other malfunction by twisting or distorting the organ.
adipose fatty cells Special cells in which fat is stored when a person's caloric intake is greater than that required by one's metabolism.
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 the body.
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 the body.
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 body.
alveoli The sacs in the lungs at the ends of the smallest airways where oxygen is exchanged for carbon dioxide in the blood.
amblyopia Impaired vision without an apparent cause.
ambulatory Able to walk. Not confined to bed.
amenorrhea Absence of menstrual periods.
amnesia Partial or total loss of memory, usually as the result of psychological trauma or stress, or physical damage to the brain from injury, disease, or alcohol or other chronic drug abuse.
amnion The membrane enclosing a developing fetus; it's filled with a protective liquid called amniotic fluid.
amputation The surgical removal of a limb or other appendage because of damage by trauma or as a treatment for a variety of potentially life-threatening ailments.
anaerobic exercise Brief, intense exercise that leads to an oxygen debt in a certain area of tissue. Weight lifting is an example.
anaphylaxis The most severe form of allergy, in which the person's heart and lungs are unable to keep working, and death occurs unless prompt medical attention is obtained.
androgen Any substance that produces male characteristics. Testosterone and androsterone are natural androgens.
anemia A decreased ability of the blood to carry oxygen because of a reduction in either the number or quality of the red blood cells.
anesthesia Drug-induced loss of feeling or sensation.
anesthetic An agent used to produce anesthesia.
aneurysm A thin sac caused by a weakened area in the walls of blood vessels or the heart. As an aneurysm increases in size, the sac tends to become thinner, and the risk of its breaking becomes greater.
angina pectoris Chest pain caused by decreased oxygen delivery to the heart muscle.
angioma A noncancerous tumor made up of many blood vessels.
anhidrosis Absence of sweating. An inability to sweat greatly interferes with the body's ability to control its internal temperature.
ankylosis Abnormal stiffening of a joint.
anomaly Deviation from normal.
anorchism Congenital absence of both testes.
anorexia nervosa An eating disorder manifested primarily by a loss of desire or willingness to eat for a variety of psychological reasons.
anosmia Loss of the sense of smell.
antepartum Occurring before delivery of a baby.
antibody A protein produced by the body to neutralize an invading foreign agent or antigen, such as a virus.
antidote An agent used to counteract a poison.
antigen A foreign agent capable of starting an immune response or causing the body to produce antibodies.
antiserum A serum that contains antibodies. Serum from a person or animal with immunity to a certain disease can, in some cases, be used to prevent illness in other people.
anus The opening of the rectum.
anxiety A feeling of nervousness, uneasiness, apprehension or dread.
aorta The large artery that carries blood from the heart to the rest of body.
apathy Lack of emotions.
Apgar score A scoring method from zero to 10 for describing the health of an infant at birth, based on heart rate, breathing, muscle tone, color and reflex irritability.
aphagia Inability to swallow.
aphasia A partial or total loss of the power to use or understand words.
aphthous ulcers A painful sore in the mouth. Also called a canker sore.
apnea Temporary pause in breathing.
appendectomy Surgical removal of the appendix.
appendix A finger-like appendage near the junction of the large intestine and the small intestine.
areola The dark area of the breast surrounding the nipple.
arteriosclerosis Commonly called "hardening of the arteries." An abnormal thickening and loss of elasticity of the wall of the arteries.
arteriovenous malformation Abnormal group of dilated blood vessels, most often occurring in the brain.
artery A vessel that carries blood away from the heart to various parts of the body.
arthralgia Pain in a joint.
arthritis Inflammation of a joint.
asbestos A fibrous material used to make fireproof materials, electrical insulation, roofing and filters. Asbestos has been linked to a type of lung cancer.
ascites Abnormal buildup of fluid in the abdomen that causes distention.
ascorbic acid Vitamin C.
asthma A chronic disorder characterized by shortness of breath, wheezing, coughing and tightness of the chest.
astigmatism An irregularity in the curvature of the lens of the eye, resulting in a blurry or distorted image.
atelectasis Collapsed lung. May occur following surgery or after a rib fracture.
atherosclerosis A form of arteriosclerosis caused by fatty deposits in the arteries.
athlete's foot A fungal infection of the skin of the feet.
atopy A predisposition to allergy that's inherited from parents. Included disorders are asthma, hay fever and eczema.
atria The upper chambers of the heart that receive blood from the veins and pass it to the lower chambers of the heart.
atrophy A decrease in the normal size of an organ. Wasting away.
aura A peculiar sensation that occurs before other symptoms. An example is the sensation of flashing lights before a migraine headache.
autoimmune disease A condition in which antibodies form against one's own cells.
autotransfusion A transfusion using the patient's own blood.
axilla The armpit.