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Medical Dictionary For: a

Word	Definition
A&D	ascending & descending
A&W	alive and well
a-	no, not, without, away from
A-P	anterior-posterior
aa.	arteries
AAA	abdominal aortic aneurysm
AAD	antibiotic associated diarrhea
AAL	anterior axillary line
ab-	away from
abd	abdominal/abdomen
abdomen	The part of the body cavity below the thorax.
abdomin-	abdomen
abdominal aorta	The part of the descending aorta passing through the diaphragm into the abdomen.
abdominal pain	Discomfort, distress, or agony in the abdominal cavity. Can be acute or chronic. A significant clinical symptom.
abdominal quadrants	Four segments of the abdomen divided by horizontal and vertical lines intersecting at the umbilicus.
abdominal thrusts	A maneuver for treating choking by using quick, forceful thrusts of fisted hands upward and inward toward the diaphragm. Commonly known as the Heimlich maneuver.
abdominal wall	The boundaries of the abdomen, consisting of multiple layers: skin, subcutaneous fat, superficial fascia, muscles, transversalis fascia, extra peritoneal fat, and the parietal peritoneum. Extends from the thoracic cage to the pelvis.
abdominoplasty	Surgical removal of excess abdominal skin and fat and tightening of the abdominal wall. Commonly called a tummy tuck.
abducens nerve	A small cranial nerve which originates in the pons and sends motor fibers to the lateral rectus muscles of the eye. It provides horizontal eye movement control.
abduction	Movement of a limb away from the midline or axis of the body.
aberration	A deviation from a normal condition or behavior.
ABG	arterial blood gas
ABI	ankle-brachial index
ablat/o	to remove, to destroy
ablation	Removal of tissue by vaporization, abrasion, freezing or other methods.
ablation techniques	Removal or disabling of body tissue by using hot liquids, microwave thermal heating, freezing, chemical ablation, and laser photoablation.
ablution	Washing the body.
ABN	abnormal
ABO	three basic blood groups
abo blood group	A major blood classification system based on the presence or absence of two antigens, A and B. Type O occurs when neither A nor B is present and AB when both are present. A and B are genetic factors that determine the presence of enzymes for the synthesis of certain glycoproteins mainly in the red cell membrane.
abortifacient	An agent, usually a medication, that causes abortion.
aBP	arterial blood pressure
abrad/o	to scrape, to wear away
abreaction	An emotional release after recollection of a repressed experience.
abscess	Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection.
absenteeism	Chronic absence from work, school or other duties.
absorption	The processes by which substances, tissue, cells, etc. take up or take in other substances or energy.
abstract	A summary of the facts, ideas and opinions presented in articles, studies, literature or presentations.
AC	adrenal cortex
-ac	pertaining to
AC (2)	anticoagulent
ac (3)	before a meal
acanth/o	thorny, sharp spine
acanthocytes	Erythrocytes with spiny projections giving the cell a thorny appearance.
acar/o	mites
acarbose	A drug prescribed in treating type 2 diabetes mellitus. It retards the digestion of complex carbohydrates.
acaridae	Family of mites frequently found in grain and flour.
accelerated idioventricular rhythm	A type of automatic, not reentrant, ectopic ventricular rhythm with episodes lasting from a few seconds to a minute. The ventricular rate is 50 to 100 beats per minute.
acceleration	A change in an object's rate of speed or direction.
accessory nerve	Either of two cranial nerves which are important for swallowing, speech and some head and shoulder movements.
acclimatization	Adaptation of an organism to a new or changing environment.
accreditation	Certification for voluntary compliance with standards established by non-governmental organizations.
acculturation	Process of accepting or assimilating cultural change.
ACE Inhibitor	Drug that lowers BP by inhibiting angiotensin converting enzyme (ACE) allowing increased blood flow
acebutolol	A beta blocker drug used to treat high blood pressure, irregular rhythms and angina pectoris.
acetabulum	Concave surface of pelvis where the head of the femur lies
acetic	Having a sour property of vinegar or acetic acid.
acetone	A colorless liquid used as a solvent and an antiseptic. Present in urine.
achilles tendon	The tendon connecting the muscles in the back of the calf to the calcaneus (heel bone).
achlorhydria	Absence of hydrochloric acid in gastric secretion.
achondroplasia	A disorder that is a form of short-limb dwarfism.
acid etching	Preparation of tooth surfaces with etching agents, such as phosphoric acid, to roughen the surface to increase adhesion.
acid-base balance	The balance between acids and bases in the body fluids. The pH of the arterial blood provides an index for the total body acid-base balance.
acid/o	acid, sour, bitter
acidosis	A pathologic condition of acidity in body fluids and tissues. The two main categories are respiratory and metabolic acidosis.
ACLS	advanced cardiac life support
acne	A common inflammation of the sebaceous glands and hair follicles.
acne conglobata	Severe, chronic acne characterized by large, burrowing abscesses associated with disfigurement. Also called cystic acne.
acne keloid	A disorder in which secondary pyogenic infection in and around pilosebaceous structures ends in keloid scarring. Often develops at the hairline on the back of the neck.
acou-	hear
acquired immunodeficiency syndrome	An acquired defect of T-cell immunity associated with infection by the human immunodeficiency virus (HIV).
acr/o	extremities, top
acrodermatitis	Chronic inflammation of the skin of the hands and feet. Caused by a parasitic mite. A manifestation of Lyme disease.
acromegaly	A hormonal disorder that results when the pituitary gland produces excess growth hormone.
acromioclavicular joint	The gliding joint formed by the outer extremity of the clavicle and the inner margin of the acromion process of the scapula. This joint has six ligaments.
acromion	The lateral extension of the spine of the scapula and the highest point of the shoulder.
acrophobia	Fear of heights
acrosome	The cap-like structure covering the anterior portion of spermatozoon. It contains enzymes necessary for sperm penetration of the egg.
act-	drive, do, act
ACTH	adrenocorticotropic hormone
actin/o	radiation, ray
actinic keratosis	Pre-cancerous patch of thick, scaly, or crusty skin secondary to extensive sun exposure
actinomycosis	A chronic bacterial disease, often found on the abdomen, thorax and jaw. Characterized by lumpy, deep abscesses that discharge pus.
actomyosin	A protein complex of actin and myosin occurring in muscle. It is the essential contractile substance of muscle.
acu-	needle
acupuncture	Therapy for treating pain and disease by inserting needles along specific pathways or meridians.
acute	severe; sudden in onset; lasting a short time
acute respiratory distress syndrome	A lung condition that causes low oxygen levels in the blood. It can be life threatening.
AD	Alzheimer disease
-ad	toward, in the direction of
ad-	toward, increase
adams-stokes syndrome	Recurring fainting spells caused by incomplete heart block.
ADD	attention deficit disorder
Addison disease	A rare disorder in which the adrenal glands do not produce enough of the hormones cortisol and/or aldosterone.
adduction	Movement of a limb toward the midline or axis of the body
adductor	A muscle that moves a body part toward the midline or axis of the body.
aden/o	gland
adenitis	Inflammation of a lymph node resulting in swelling or pain.
adenocarcinoma	A malignant epithelial tumor with a glandular growth pattern.
adenoid/o	adenoids
adenoidectomy	Surgical removal of the adenoids.
adenoids	A collection of lymphoid nodules on the posterior wall and roof of the nasopharynx..
adenoma	A benign epithelial tumor with a glandular structure
adenovirus	Virus responsible for upper respiratory tract infections, conjunctivitis, cystitis or GI infection.
ADH	antidiuretic hormone
ADHD	attention deficit-hyperactivity disorder
adhesion	Bands of scar tissue that can develop after surgery.
adip/o	fat
adipose	Connective tissue composed of fat cells.
adiposity	The amount of fat or lipid deposit at a site or an organ.
adjustment disorders	Maladaptive reactions to a stressful event.
ADL	activities of daily living
adnexa	Appendages of an organ (e.g. eyelids to the eyeball)
adolescence	A period beginning with puberty and ending at maturity. Usually from 11-13 years of age and ending at 18-20 years of age.
adren/o	adrenal glands
adrenal	Pertaining to the adrenal glands, which are located atop of the kidneys.
adrenalectomy	Surgical removal of one or both adrenal glands.
adrenalitis	Inflammation of the adrenal glands,
adrenarche	A development stage when the adrenal glands mature, leading to the increased production of adrenal androgens, dehydroepiandrosterone and androstenedione. Adrenarche usually begins at about 7 or 8 years of age before the signs of puberty and continues throughout puberty.
adrenergic fibers	Nerve fibers liberating catecholamines at a synapse after an impulse.
adrenergic neurons	Neurons whose primary neurotransmitter is epinephrine.
adsorption	The adhesion of gases, liquids, or dissolved solids onto a surface.
adult	A person having attained maturity.
advanced cardiac life support	The use of sophisticated methods and equipment to treat cardiopulmonary arrest. Advanced Cardiac Life Support (ACLS) includes the use of specialized equipment to maintain the airway, early defibrillation and pharmacological therapy.
adventitia	The outermost covering of organs, blood vessels and other structures not covered by serosa.
AE	above elbow
AED	automated external defibrillator
aer-	air
aerobics	Sustained strenuous exercise that improves cardiovascular and respiratory fitness.
aerophagia	Excessive swallowing of air.
aerophagy	Excessive swallowing of air caused by anxiety or improper eating habits.
AF	atrial fibrillation
AFB	acid-fast bacillus
affect	The emotional reaction to an experience or thought.
Afib	atrial fibrillation
afibrinogenemia	A deficiency or absence of fibrinogen in the blood.
AFP	alpha-fetoprotein
afterbirth	The placenta, umbilical cord and membranes that are expelled from the uterus after birth
aftercare	Health care provided to a patient after discharge.
ageusia	Loss of the sense of taste.
agglutin/o	clumping
aggression	Forceful verbal or physical behavior, or an overt attitude of hostility.
agit/o	rapidity, restlessness
agnosia	The inability to comprehend or recognize the importance of various forms of stimulation.
-agogue	simulator, agent causing change
agonal	Relating to conditions and struggles preceding death.
agonistic	A muscle whose contraction causes movement of a body part. Also, a drug that combines with receptors to produce an action.
agoraphobia	Obsessive, intense fear of open places or leaving home..
-agra	severe pain
agraphia	Inability to write due to a cerebral injury or less commonly, due to emotional factors.
AHA	American Hospital Association
AHF	antihemophilic factor
AIDS	acquired immunodeficiency syndrome
AIHA	autoimmune hemolytic anemia
air	The mixture of gases present in the earth's atmosphere consisting of oxygen, nitrogen, carbon dioxide, and small amounts of other gases.
air sacs	Thin-walled spaces including the alveoli connected to one terminal bronchiole.
airway	Tubular passages in the lungs through which air passes during breathing.
AIVR	accelerated idioventricular rhythm
AK	above the knee
akinetic mutism	A syndrome characterized by a silent and inert state without voluntary motor activity despite alertness.
Al	aluminum
-al	relating to
alacrima	Dry eye.
albin/o	white, deficient pigmentation
albinism	Genetic disorders causing the skin, hair, or eyes to have little or no color.
albumin	Proteins found in egg whites, milk, blood, lymph, and other tissues and fluids. They are water soluble and coagulate upon heating.
albuminuria	The presence of albumin in the urine, an indicator of kidney diseases.
albuterol	A short-acting beta-2 adrenergic agonist that is primarily used as a bronchodilator agent to treat asthma.
alcoholism	A primary, chronic disease creating a physical dependence on alcohol. Genetic and environmental factors influence its development.
aldosterone	A hormone secreted by the adrenal cortex that acts on the kidneys to regulate electrolyte and water balance.
aldosteronism	A disease that causes the adrenals to produce too much of the hormone aldosterone.
alexia	Inability to read despite preservation of the ability to write. The patient cannot recognize letters and words.
ALF	assisted living facility
-algesia	pain
-algia	pain
algid	Cold, clammy skin associated with some types of malaria.
alginate	A salt of alginic acid extracted from marine kelp. Used for surgical dressings.
algorithm	A step-by-step protocol for managing health care problems.
alienation	Lack of meaningful relationships with others, leading to estrangement.
aliment/o	nutrition
alimentary canal	The passage for the digestion and absorption of food. Extends from mouth to anus.
alkaloids	Organic nitrogenous bases produced by plants and used to create important, powerful drugs.
alkalosis	A condition of high alkalinity of blood and other body fluids.
ALL	acute lymphocytic leukemia
allergen	Antigen-type substance that produce immediate hypersensitivity.
allergy	Hypersensitive reaction to common substances that are in the environment or digested. Also, an acquired sensitivity to certain drugs.
allied health personnel	Health care workers specially trained and licensed to provide patient services in specialties such as physical therapy, laboratory sciences, dental hygiene and emergency services.
allo-	other
alloantigen	An antigen that occurs in some but not all members of a species.
allograft	Tissues, cells, or organs transplanted between genetically different individuals of the same species.
allopathy	A medical therapy system in which a disease is treated by creating a second condition in the body that opposes the disease.
allopurinol	A xanthine oxidase inhibitor that decreases uric acid production. Used to treat gout and kidney stones.
aloe	The dried juice of aloe plant leaves. Used to treat minor wounds, burns and skin irritations.
alopecia	A disorder in which the immune system attacks hair follicles in the scalp.
alphavirus	A group of small Toga viruses. Can be transmitted from mosquitoes to humans, causing several types of encephalitis.
alprazolam	A compound used to treat anxiety.
alprostadil	A potent vasodilator agent that increases peripheral blood flow.
altitude sickness	Multiple symptoms associated with reduced oxygen at high altitude. These symptoms include headache, nausea, fatigue, difficulty sleeping, tachycardia and shortness of breath.
alve-	channel, cavity
alveol/o	alveolus
alveoli	Air sacs in the lung which allow exchange of blood oxygen and carbon dioxide.
alveolitis	An inflammation of the alveoli. Caused by inhalation of an allergen.
Alzheimer disease	Type of dementia that causes problems with memory, thinking, and behavior.
AM	morning
AMA	American Medical Association
amalgam	A mixture of mercury, silver and other metals used in dentistry.
amanita	A genus of mushrooms. Some species are poisonous.
amantadine	An antiviral agent used to treat influenza A. Also used as an antiparkinsonian agent.
amaurosis	Partial or complete blindness caused by a disease.
amber	A hard, yellowish fossil resin from pine trees.
ambi-	both, both sides, around
ambient	Pertaining to the environment of an organism or mechanism.
ambivalence	Conflicting feelings or attitudes towards a person, object or idea.
ambly/o	dull, dim
amblyopia	Decrease of vision due to abnormal development during childhood. Also known as lazy eye.
ambul/o	walking
ambulance	A vehicle for transporting patients for treatment.
ambulatory	Able to walk.
ameba	A large genus of protozoa found in water and moist conditions. Several species may be parasitic in humans.
amebiasis	Infection with ameba. Widespread condition in tropical countries.. An asymptomatic condition in most people but diseases ranging from diarrhea to dysentery.
amebicide	A drug or other agent which destroys ameba, particularly parasitic species.
ameloblastoma	A fast growing epithelial tumor of the jaw.
amelogenesis	The formation of dental enamel by ameloblasts.
amenorrhea	Absence of menstruation.
ametropia	An eye problem caused by faulty refraction.
AMI	acute myocardial infarction
amino acid	A group of organic compounds that contain an amino and a carboxyl group.
aminoglycoside	Antibiotic that prevents bacteria from producing proteins. Requires monitoring due to side-effects.
aminophylline	A bronchodilator. Used to treat asthma and COPD.
AML	acute myelogenous leukemia
amnesia	Loss of memory due to brain injury or emotional trauma.
amni/o	amnion, sac around embryo
amniocentesis	Diagnostic test for chromosomal abnormalities and fetal infections. A small amount of fluid is removed from the amniotic sac.
amniotic fluid	A clear, yellowish liquid that surrounds the fetus, protecting it from injury.
amobarbital	A barbiturate sedative-hypnotic.
amoxicillin	An oral semisynthetic penicillin antibiotic.
ampere	A measure of electrical current. One ampere (amp) is equal to the current flowing through a one ohm resistance when an electrical potential of one volt is applied.
amphetamine	A powerful group of drugs that stimulate the central nervous system. Amphetamines reduce feelings of fatigue and increase alertness.
amphi-	both sides
ampho-	both sides, double
ampicillin	Semisynthetic penicillin that functions as a broad-spectrum antibiotic.
amputation	The removal of a limb or other body appendage.
amyl-	starch
amylase	A group of enzymes that help digest starches.
amyloid	Starch-like.
amyloidosis	A group of infectious diseases cause abnormal protein folding and deposition of amyloid. These amyloid deposits can enlarge and displace normal tissue, impairing function.
amylose	The soluble constituent of starch.
amyotrophic lateral sclerosis	A neurological disease causing muscle weakness and impacting physical function. Commonly called ALS.
-an	pertaining to
an-	not, without, away from
an/o	anus, ring
ANA	antinuclear antibody
ana-	up, apart, again
anabolic steroid	A compound derived from testosterone or synthetically that stimulates development of muscle mass, strength, and power.
anacrotism	A secondary notch in the pulse curve, obtained in a pulse tracing.
anaerobic	Taking place without oxygen.
anal canal	The terminal segment of the large intestine ending at the anus.
analgesia	Without pain or decreased pain.
analgesics	A compound that relieves pain.
anaphylaxis	A severe immune system reaction to a previously encountered antigen. Can sometimes be fatal.
anaplasia	Loss of structural differentiation and useful function of neoplastic cells. Typical of malignant tumors.
anasarca	Massive swelling (edema) of the legs, truck and genitalia. Occurs in congestive heart failure, renal disease or liver failure.
anastomosis	A surgical connection between two structures.
anatomy	The study of the structure of organisms.
anconeus	A small triangular muscle behind the elbow. Its function is to extend the forearm.
andr/o	male
andro-	male
androgen	Steroid hormones that stimulate development of male reproductive organs, beard growth, voice changes and muscles.
android	Pertaining to something human.
andropause	Male menopause.
androsterone	A metabolite of testosterone or androstenedione.
anemia	Blood lacks enough erythrocytes (RBC) or hemoglobin.
aneroid	A kind of barometer operated by the movement of the elastic lid of a box exhausted of air.
anesthesia	The loss of feeling or sensation, particularly pain.
anesthesiology	A specialty concerned with the study of anesthetics and anesthesia.
anesthetic	Medication that causes temporary loss of sensation.
anesthetics	Agents that are capable of inducing a total or partial loss of sensation, especially tactile sensation and pain. They may act generally or locally.
anetoderma	Benign dermatosis caused by a loss of dermal elastic tissue resulting in localized sac-like areas of flaccid skin.
aneurysm	A sac-like dilatation of a blood vessel wall. It indicates a weak spot in the wall which may rupture.
anger	A strong emotional feeling of displeasure aroused by being interfered with, injured or threatened.
angi/o	blood or lymph vessel
angina pectoris	Chest pain, pressure, or squeezing, often due to ischemia of the heart muscle.
angiocardiography	Radiography of the heart and great vessels after injection of a contrast medium.
angioedema	Swelling involving the deep dermis, subcutaneous, or submucosal tissues, representing localized edema. It often occurs in the face, lips, tongue, and larynx.
angiography	An x-ray study of blood vessels after injection of a contrast medium.
angiokeratoma	A benign vascular, horny neoplasm of the skin often found on the legs and feet.
angioma	A usually benign tumor consisting of blood vessels and lymph nodes.
angiomyoma	A benign tumor consisting of vascular and smooth muscle elements.
angioplasty	Repair of a blood vessel such as widening a narrowed artery or vein. This procedure is normally performed using catheterization.
angioscope	An endoscope used for viewing the interior of blood vessels.
angiostenosis	Abnormal narrowing of a blood vessel.
angiotensin	A family of peptides in the blood that causes vasoconstriction and increased blood pressure.
angstrom	A unit of length equal to 0.1 nanometer.
anhedonia	Inability to experience happiness or pleasure. It is a symptom of many psychotic disorders.
anhidrosis	Absence of sweating in an environment appropriate for sweating.
anion	Negatively charged ion.
anis-	unequal
anisocoria	Unequal pupil sizes. Affects 20% of the population.
ankle	The region between the foot and leg.
ankle brachial index	The ankle-arm index. This is the ratio of the higher of the two ankle systolic blood pressures divided by the higher of the two arm systolic pressures. It is a predictor of peripheral arterial disease.
ankyl/o	bent, stiff
ankylosis	Fixation and immobility of a joint.
anodontia	Congenital absence of most or all teeth.
anomal/o	irregular
anomaly	A variation from normal, particularly congenital defect
anomia	An inability to name people and objects that are correctly comprehended.
anorexia	The lack or loss of appetite with an inability to eat.
anorexia nervosa	An eating disorder characterized by a loss of appetite and an excessive fear of becoming overweight.
anosmia	loss or impairment of the sense of smell. It can be temporary or permanent.
anovulation	Suspension or cessation of ovulation by the ovaries.
anoxia	Absence of oxygen in body tissues despite adequate blood flow.
ant.	anterior
antacids	Substances that neutralize acidity in the stomach.
antagonist	A person, muscle or drug that opposes another.
antazoline	A short acting antihistamine
ante-	forward, before
antegrade	Moving forward or moving in the direction of blood or urine flow.
antepartal care	Health care provided during pregnancy.
anter/o	front
anterior	front
anterior chamber	The space between the cornea and the iris, filled with aqueous humor.
anterior cruciate ligament	A strong ligament of the knee that extends from the anterior intercondylar area of the tibia to the posterior part of the medial surface of the lateral condyle of the femur. Responsible for controlling stability during knee rotation.
anthelmintics	Agents that destroy or prevent development of parasitic worms.
anthrac/o	carbon, coal
anthracosis	A chronic lung disease caused by inhaled coal dust. Occurs in coal miners but also in tobacco smokers.
anthrax	An acute infectious disease of hoofed animals and humans. Infection in humans often involves the skin , lungs or gastrointestinal tract.
anthrop/o	human life
anti-	against
anti-inflammatory	Reducing inflammation.
antibiotics	An infection fighting protein made by blood plasma cells in response to an antigen. It helps destroy bacteria, viruses and toxins.
antibodies	Immunoglobulin molecules produced in lymphoid tissue that attack the antigen that induced their synthesis.
antibody	Protein produced by B cells as primary immune defense.
anticoagulants	Agents that slow coagulation and prevent blood clotting.
anticonvulsants	Drugs used to prevent seizures or reduce their severity.
antidepressants	Drugs that prevent or relieve depression.
antidiabetic	Drugs that help control diabetes mellitus.
antidiarrheal	A drug or food for treating diarrhea.
antidiuretic hormone	A hormone produced by the hypothalamus and stored in the pituitary gland. This hormone controls the amount of water excreted in the urine.
antidromic	Conducting nerve impulses in a direction opposite from normal.
antiemetics	Drugs used to prevent nausea or vomiting.
antifibrinolytic	Preventing the breakdown of a blood clot or thrombus.
antifungal	Substances that destroy fungi.
antigen	Substances that are recognized by the immune system and induce an immune reaction.
antigens	Substances that are recognized by the immune system and induce an immune reaction.
antihistamine	An agent that inhibits the actions of a histamine.
antihypertensive	Drugs used to reduce high blood pressure.
antimitotic	Drugs that arrest cell division.
antioxidant	Substances that inhibit oxidation of a substance.
antiparasitic	A drug used to treat or prevent parasitic infections.
antiperspirants	Agents that are put on the skin to reduce sweating.
antipruritic	An agent that relieves itching. Usually topical.
antipsychotic	An agent used to control severe mental disorders.
antipyretic	A drug used to reduces fever.
antisepsis	The destruction of germs causing disease.
antisocial	A personality disorder characterized by a disregard for individual rights or laws.
antispasmodic	A drug used to treat smooth muscle spasms in the digestive system, uterus or urinary tract.
antithyroid	An agent used to treat hyperthyroidism.
antitoxins	Antisera from immunized animals that is purified and used as a passive immunizing agent against specific bacterial toxins.
antitussive agents	Cough medicine that acts centrally on the medullary cough center.
antiviral	Destroying a virus or suppressing replication.
antr/o	antrum, cavity
antrum	A cavity or chamber.
anuria	Absence of urine formation.
anus	The distal opening of the alimentary canal, lying in the fold between the buttocks.
anxiety	Feeling or emotion of dread, apprehension, or fear without apparent stimulus.
anxiety disorders	A group of mental disorders characterized by feelings of anxiety and fear.
Ao	aorta
AODM	adult-onset diabetes mellitus
aort/o	aorta
aorta	The main trunk of the systemic arteries originating at the heart's left ventricle.
aortic aneurysm	An abnormal balloon or sac-like dilatation in the aortic wall.
aortic coarctation	A congenital heart abnormality where the aorta is narrowed.
aortic stenosis	Narrowing of the aortic valve opening, reducing outflow from the left ventricle into the aorta.
aortic valve	The valve between the left ventricle and the aorta. It prevents back flow of blood into the left ventricle.
aortic valve regurgitation	Back flow of blood from the aorta into the left ventricle.
APA	antipernicious anemia factor
apache	An acronym for Acute Physiology and Chronic Health Evaluation, a scoring system used for classifying the severity of illness in critically ill patients.
apathy	Lack of emotion or emotional expression; disinterest.
apex	The tip of an organ.
Apgar score	Newborn health assessment score (0-10). Two points each: Appearance of skin color, Pulse, Grimace, Activity, Respiration.
aphakia	Absence of the eye's lens.
aphasia	Impairment of language or speech comprehension.
-apheresis	separation, removal
aphonia	Inability of the larynx to produce speech sounds.
aphrodisiac	An agent that stimulates sexual desire.
aphth/o	ulcer
apic/o	apex
apical	Pertaining to the tip or apex of a structure.
aplasia	Defective development of an organ or tissue.
aplastic anemia	A condition in which bone marrow doesn't produce sufficient blood elements.
apnea	A temporary cessation of spontaneous respiration.
apo-	separate, away from
apocrine glands	Sweat glands that only occur in hairy parts of the body.
apophysis	An outgrowth or projection from a bone.
apoptosis	Programmed cell death resulting in the orderly removal of cells.
append/o	appendix
appendectomy	Surgical removal of the appendix.
appendicitis	Acute inflammation of the vermiform appendix.
appendix	A worm-like blind tube extension from the cecum.
appetite	Natural recurring desire, e.g. for food.
apraxia	Disorders characterized by the inability to make skilled, purposeful movements due to a cerebral disease.
aprepitant	A drug used to treat chemotherapy induced nausea.
aptitude tests	Standardized tests designed to predict an individual's learning ability or performance.
aq	water
aquaphobia	An irrational fear of water.
aque/o	water
aqueous humor	The clear, watery fluid circulating in the anterior and posterior chambers of the eye.
-ar	pertaining to
arachnoid	A delicate membrane covering the brain and spinal cord. It lies between the pia mater and the dura mater.
arachnoiditis	Acute or chronic inflammation of the arachnoid membrane, resulting in pain and neurological abnormalities.
arbor	A tree-like structure with branching.
arbovirus	Viruses transmitted by saliva of insects, bats and rodents.
ARC	AIDS-related complex
arch-	beginning, origin, first
ARDS	acute respiratory distress syndrome
areola	A ring of pigmented skin surrounding a nipple.
ARF	acute renal failure
argon	An odorless, colorless, inactive gas with atomic number 18.
argyria	A permanent ashen-gray discoloration of the skin, conjunctiva, and internal organs due to ingestion of or exposure to silver salts.
arm	The superior part of the upper limb between the shoulder and the elbow.
ARMD	age-related macular degeneration
aromatherapy	The use of fragrances and plant oils to improve physical, mental, and emotional well-being.
arousal	A state of alertness due to stimulation.
arrhythmia	Abnormal heartbeat rhythm.
arsenic	A shiny gray element with atomic symbol As, atomic number 33. Most forms are toxic.
arteri/o	artery
arterial blood gases	A test that measures the levels of oxygen, carbon dioxide and acidity (pH) in the blood. Some blood gases devices make additional measurements available.
arteries	The vessels carrying blood away from the heart.
arteriol/o	small artery
arterioles	The smallest divisions of the arteries located between the muscular arteries and the capillaries.
arteriolosclerosis	Thickening of the walls of small arteries or arterioles.
arteriosclerosis	Thickening and stiffening of arterial walls.
arteriostenosis	Narrowing of arterial walls.
arteritis	inflammation of one or more arteries.
arthr/o	joint
arthralgia	Joint pain.
arthritis	Inflammation of joints, characterized by pain, swelling and diminished range of motion.
arthrocentesis	Aspiration of fluid (e.g., synovial fluid) from a joint cavity.
arthrodesis	The surgical fixation of a joint by a procedure designed to accomplish fusion of the joint surfaces by promoting the proliferation of bone cells.
arthrography	Imaging of a joint, usually after injection of a contrast medium.
arthrolysis	Surgical restoration of mobility in stiff, ankylosed joints.
arthroplasty	Surgical reconstruction of a joint to relieve pain or restore motion.
arthropod	A member of the phylum Arthropoda, composed of organisms having a hard, jointed exoskeleton and paired jointed legs. It includes insects, mites, ticks and spiders.
arthroscopy	Examination, therapy and surgery of a joint using an endoscope.
articul/o	joint
articulation	The junction of two or more bones. Also, forming sounds into meaningful speech.
artifacts	Anything artificially made. An unwanted problem with a medical imaging technique.
artificial limbs	Prosthetic replacements for arms and legs.
-ary	pertaining to
AS	aortic stenosis
ASA	acetylsalicylic acid
asbestosis	Lung disease characterized by interstitial fibrosis. Caused by inhalation of asbestos particles.
ASC	atypical squamous cells
ASC-US	atypical squamous cells of undetermined significance
ascites	Abnormal accumulation of free fluid within the peritoneal cavity.
ascorbic acid	A water soluble compound. As vitamin C, it naturally occurs in citrus fruits and many vegetables.
ASD	atrial septal defect
-ase	enzyme
aspartame	Artificial sweeter, metabolized as phenylalanine and aspartic acid.
asperger syndrome	A developmental disorder whose essential features are persistent impairment in reciprocal social interactions, and restricted, repetitive patterns of behavior, interests, or activities and impairment in language and communications skills.
aspermia	A condition characterized by the complete absence of semen.
asphyxia	Condition caused by lack of oxygen, leading to loss of consciousness and death. Causes include drowning, suffocation, choking and inhaling carbon monoxide.
aspir/o	inhaling
aspirin	An analgesic, anti-inflammatory and antipyretic agent. It also reduces the risk of vascular thrombosis.
assault	A violent physical or verbal attack.
assertiveness	Strongly insistent, self-assured behavior.
assimilation	The transformation of food into living tissue.
Ast	astigmatism
astasia	The inability, without physical cause, to stand or sit without assistance.
asthen-	weakness
asthma	Chronic bronchial inflammatory disorder. Characterized by breathing difficulty, wheezing, coughing and dyspnea.
astigmatism	A common and generally easily treatable imperfection in the curvature of the eye.
astr/o	star
astringent	A drug, usually topical, that cause the contraction of tissues. Used for controlling bleeding or secretions.
astrocyte	A large, star shaped cell. Found throughout the central nervous system.
astrocytoma	A type of brain tumor.
asystole	Complete absence of cardiac output and electrical activity in the heart.
ataxia	Inability to coordinate voluntary muscle movements, not due to muscle weakness.
atc	around the clock
atelectasis	Partial or complete failure of a lung to expand due to alveoli deflation. Can occur after surgery, trauma, infections.
ateliosis	A form of dwarfism.
atelo-	incomplete, imperfect
ather/o	plaque, soft fatty deposit
atherectomy	Endovascular procedure for removing atheromatous plaque by a cutting or rotating catheter.
atheroma	A thickening and loss of elasticity of arterial walls due to plaque deposits. Also called atherosclerosis.
atherosclerosis	A thickening and loss of elasticity of arterial walls due to plaque deposits.
athetosis	Slow, continuous slow, flowing involuntary movements of the fingers, toes, tongue and face. Often a form of cerebral palsy. While impairing speech, intelligence in often unaffected.
ATL	adult T cell leukemia
atmo	steam, vapor
atonic	Without normal muscle tone or strength
atorvastatin	A drug used to reduce the levels of cholesterol and triglycerides in the blood.
atresia	The absence or abnormal narrowing of a body opening or duct.
-atresia	closure, occlusion
atreto-	closed
atri/o	atrium
atria	The upper chambers of the heart which receive blood flow from the body.
atrial fibrillation	Abnormal cardiac rhythm characterized by rapid, uncoordinated firing of electrical impulses in the atria. Increases risk of stroke and heart disease.
atrial flutter	A very rapid, irregular heart rhythm. A common form of tachyarrhythmia.
atrioventricular node	A small group of specialized muscle fibers located on the floor of the right atrium. It regulates electrical signals to the ventricles, preventing rapid conduction and ensuring that the atria have emptied.
atrium	(of the heart). Either of the two upper chambers of the heart.
atrophy	Diminished size or wasting away of body tissue, for example muscles.
attention	Mentally focusing on a specific object, issue or activity. The act of concentrating.
attenuation	The reduction or dilution of disease producing ability.
attitude	1) A position or posture of the body. 2) A way or manner of behaving.
attrition	Wearing away.
atypical	Unusual. Not representative of a type or group.
Au	gold
audi/o	hearing
audiology	The study of hearing and hearing impairment.
audiometry	A noninvasive test that measures the ability to hear different tones and intensities.
audit	A formal review of data or records.
augmentation	The process of increasing in size or amount.
AUL	acute undifferentiated leukemia
aur/o	ear
aural	Refers to the ear or hearing.
auranofin	A drug for treating rheumatoid arthritis.
ausc	auscultation
auscultation	Listening for body sounds usually with a stethoscope.
autism	A group of developmental disabilities that can cause significant social, communication and behavioral problems.
auto-	self, same
autoantibody	An antibody that react with self-antigens of the organism that produced them.
autoantigens	Endogenous tissue constituents that have the ability to interact with autoantibodies and cause an immune response.
autograft	Transplant comprised of an individual's own tissue, transferred from one part of the body to another.
autoimmune	Disorder of the immune system in which an immune response is created against the body's own tissues.
autoimmune disorder	Immune system attacks on healthy cells by mistake.
autoimmunity	Process whereby the immune system reacts against the body's own tissues.
autologous	One individual being both donor and recipient (e.g. blood).
autolysis	The disintegration of tissues or cells by intracellular enzymes.
automatism	Automatic, mechanical, and apparently undirected behavior which is outside of conscious control.
autonomic	The ability to function without external influence.
autonomic nervous system	The part of the nervous system that regulates involuntary body functions. The enteric nervous system; parasympathetic nervous system; and sympathetic nervous system taken together.
autonomy	Ability to function independently. Self-governing.
autophagia	Biting or eating one's own flesh.
autopsy	Postmortem examination of the body to determine the cause of death.
autosome	Any chromosome that is not a sex chromosome and that occurs in pairs in somatic cells.
autosuggestion	Suggestion coming from the subject himself.
autotrophic	Self nourishing. The processes by which organisms use inorganic substances such carbon dioxide and inorganic nitrogen as nutrient sources.
aux/o	growth
AV	atrioventricular
avascular	An area of the body lacking adequate blood vessels or blood supply.
AVB	atrioventricular block
aversion therapy	A treatment that suppresses undesirable behavior by simultaneously exposing the subject to unpleasant consequences.
avian influenza	A highly contagious disease of poultry and other birds, caused by strains of influenza A virus.
avitaminosis	Disease caused by vitamin deficiency.
avoidance	A psychological or physical defense mechanism for avoiding a noxious experience.
AVR	accelerated ventricular rhythm
axi/o	axis
axial	Pertaining to an axis.
axill/o	armpit
axilla	Armpit.
axon	Nerve fiber that conduct impulses away from the neuron cell body.
azoospermia	A complete absence of sperm in the ejaculate.
azot/o	nitrogen
azotemia	A biochemical abnormality referring to an elevation of blood urea nitrogen and creatinine.