Abdomen  - area between the chest and the hips that contains the stomach, small intestine, large intestine, liver, gallbladder, pancreas, and spleen.

Abdominal bracing - technique of tensing the stomach muscles to support the spine.

Abdominal hysterectomy - the uterus is removed through the abdomen via a surgical incision.

Abdominoscopy - a type of surgery that uses a laparoscope, which is inserted into one or more small incisions, to examine the abdominal cavity. (see also endoscopy, laparoscopy, or minimally invasive surgery.)

Ablation - elimination or removal.

Ablative therapy - treatment that removes or destroys the function of an organ, as in surgical removal of the ovaries or the administration of some types of chemotherapy that causes the ovaries to stop functioning.

Absorption - the way substances pass into tissue as nutrients from food move from the small intestine into the cells of the body.

Abutment teeth - the surrounding teeth of each side of the gap where teeth are missing.
Accessory digestive organs - organs that help with digestion but are not part of the digestive tract. These organs include the tongue, glands in the mouth that make saliva, pancreas, liver, and gallbladder.

Accessory movement - joint movements that cannot be performed voluntarily or in isolation by the patient.

Accommodation - the ability of the eye to focus.

Acetylcholine - a chemical in the brain that acts as a neurotransmitter by sending nerve signals.

Acquired deafness - loss of hearing that occurs or develops over the course of a lifetime; deafness not present at birth.

Action tremor - a tremor that increases when the hand is moving voluntarily.

Activated charcoal - an over the counter product that may help relieve intestinal gas.

Activities of daily living (adls) - personal care activities necessary for everyday living, such as eating, bathing, grooming, dressing, and toileting; a term often used by healthcare professionals to assess the need and/or type of care a person may require.

Adenocarcinoma - a cancer that develops in the lining or inner surface of an organ.

Adenoma - benign growth starting in the glandular tissue. (see also fibroadenoma.)

Adjuvant treatment - treatment that is added to other therapies to increase effectiveness, such as chemotherapy, radiation therapy, or hormone therapy.

Adrenal cortex - the outer portion of the adrenal gland that secretes hormones that are vital to the body.

Advanced cancer - stage of cancer in which the disease has spread from the primary site to other parts of the body.

Aerophagia - condition that occurs when a person swallows too much air; causes gas and frequent belching.

Agonist - a drug capable of combining with receptors to initiate an action that can be known in advance.

Aguesia - loss of the sense of taste.

Akinesia - no movement.

Alactasia - inherited condition involving the lack of the enzyme needed to digest milk sugar.
Alimentary canal - digestive tube.

Allodynia - a condition in which ordinary, non-painful stimuli evoke pain.

Allogeneic bone marrow transplantation - a procedure in which a person receives stem cells from a compatible donor.

Alternative medicine - any form of therapy used alone, without recommended standard/conventional treatment.

Amenorrhea - absence or cessation of menstrual periods.

American cancer society - an organization that supports research, educational materials, and programs, and offers many other services to cancer patients and their families.

American sign language (asl) - manual (hand) language with its own syntax and grammar used primarily by persons who are deaf.

Amsler grid - a chart featuring horizontal and vertical lines used to test vision.

Amyloidosis - a rare disease which causes the build-up of amyloid, a protein and starch, in tissues and organs.

Anal fistula - channel that develops between the anus and the skin. Most fistulas are the result of an abscess (infection) that spreads to the skin.

Androgen - a hormone that promotes the development and maintenance of male sex characteristics.

Anesthesia - loss of feeling or sensation as a result of drugs or gases. General anesthesia causes loss of consciousness; local or regional anesthesia causes loss of feeling only to a specified area.

Anesthetics - drugs that cause loss of sensation to pain or awareness.

Angiotensin-converting enzyme (ace) inhibitor - a medication that lowers blood pressure.

Ankle sprain - overstretched lateral (outside) ligament of the ankle joint.

Anosmia - absence of the sense of smell.

Antacids - medicines that balance acids and gas in the stomach.

Anterior chamber of the eye - the front section of the eye's interior where aqueous humor flows in and out of providing nourishment to the eye and surrounding tissues.

Antibiotic - chemical substances, produced by living organisms or synthesized (created) in laboratories, for the purpose of killing other organisms that cause disease.

Anticholinergics - medicines that calm muscle spasms in the intestine.

Anticoagulant (also called blood thinner.) - a medication that keeps blood from clotting.

Antidiarrheals - medicines that help control diarrhea.

Antiemetic - drug that prevents or relieves nausea and vomiting (emesis).

Antihistamine drugs - a group of drugs that block the effects of histamine, a chemical released in body fluids during an allergic reaction.

Antihypertensive - a medication, or other therapy, that lowers blood pressure.

Anti-inflammatory drugs - inflammatory drugsdrugs that reduce the signs and symptoms of inflammation.

Antimetabolites - substances that interfere with the body’s chemical processes, such as creating proteins, dna, and other chemicals needed for cell growth and reproduction.

Antioxidants - compounds that protect against cell damage inflicted by molecules called oxygen-free radicals, which are a major cause of disease and aging.

Antispasmodics - medicines that help reduce or stop muscle spasms.

Antrectomy - operation to remove the upper portion of the stomach, called the antrum, often to help reduce the amount of stomach acid.

Anus - opening at the end of the digestive tract where bowel contents leave the body.

Aorta - blood vessel that delivers oxygen-rich blood from the left ventricle to the body; it is the largest blood vessel in the body.

Aortic valve - the valve that regulates blood flow from the heart into the aorta.

Apex - top portion of the upper lobes of the lungs.

Aphasia - total or partial loss of ability to use or understand language; usually caused by stroke, brain disease, or injury.

Aphonia - complete loss of voice.

Apraxia - inability to make a voluntary movement in spite of being able to demonstrate normal muscle function.

Areola - dark area of skin that surrounds the nipple of the breast.

Arterioles - small branches of arteries.

Artery - a blood vessel that carries oxygenated blood away from the heart to the body.

Arthralgia - pain in a joint, usually due to arthritis or arthropathy.

Arthroplasty - total joint replacement.

Articular cartilage - covers the ends of bones and allows the distribution of compressive loads over the cross section of bones; provides frictionless and wear-resistant surface for joint movement.

Articulation disorder - inability to correctly produce speech sounds (phonemes) because of imprecise placement, timing, pressure, speed, or flow of movement of the lips, tongue, and/or throat.

Artificial ventilation - the process of supporting breathing by manual or mechanical means when normal breathing is inefficient or has stopped.

Ascending colon - part of the colon on the right side of the abdomen.

Assisted reproductive technology (art) - medical procedures, such as intrauterine insemination, that are performed to help infertile couples conceive.

Assistive devices - technical tools and devices such as alphabet boards, text telephones, or text-to-speech conversion software used to assist people with physical or emotional disorders in performing certain actions, tasks, and activities.

Atherectomy - a non-surgical procedure that involves removing plaque from the walls of arteries with a rotating blade.

Atherosclerosis - a type of arteriosclerosis caused by a build-up of plaque in the inner lining of an artery.

Athetosis - slow, involuntary movements of the hands and feet.

Atonic colon (also called lazy colon.) - lack of normal muscle tone or strength in the colon.

Atresia - lack of a normal opening from the esophagus, intestines, or anus.

Atrioventricular (av) node - a cluster of cells between the atria and ventricles that regulate the electrical current.

Atrioventricular block - an interruption of the electrical signal between the atria and the ventricles.

Atrium (pl. Atrial) - one of two upper chambers in the heart.

Atrophic gastritis - chronic inflammation of the stomach that causes the breakdown of the mucous membranes of the stomach.

Atrophy - a continuous decline of a body part or tissue, usually a muscle, following a period of disuse or immobility.

Atypical - not usual; abnormal; often refers to the appearance of pre-cancerous or cancerous cells. (see also hyperplasia.)

Auditory brainstem response (abr) test - test used to screen for hearing impairments in infants and young children.

Auditory nerve - eighth cranial nerve that connects the inner ear to the brainstem.

Auditory perception - ability to identify, interpret, and attach meaning to sound.

Auditory prosthesis - device that substitutes or enhances the ability to hear.

Augmentative devices - tools that help individuals with limited or absent speech to communicate.

Aural rehabilitation - techniques used with people who are hearing impaired to improve their ability to speak and to communicate.

Autoimmune process - a process where the body's immune system attacks and destroys body tissue that it mistakes for foreign matter.

Autologous transplant - a procedure in which a patient's own bone marrow is removed, treated with anticancer drugs or radiation, then returned to the patient.

Autopsy - examination of a body after death; performed to determine cause of death, or to verify a diagnosis.

Avascular necrosis - death of tissue due to a depletion of blood supply.

Avulsion - when a muscle is forcefully stretched beyond its freely available range of motion, or when it meets a sudden, unexpected resistance while contracting forcefully.

Axilla - armpit.

Axillary dissection - a surgical procedure in which the lymph nodes in the armpit (axillary nodes) are removed and examined; often used to determine if breast cancer has spread to the axillary nodes.

Axon - the long, hair like extension of a nerve cell that carries a message to a nearby nerve cell.