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Medical terminology is composed of a prefix, root word, and suffix:
Prefix: A prefix is placed at the beginning of a word to modify or change its meaning. Pre means "before." Prefixes may also indicate a location, number, or time.
Root: central part of a word.
Suffix: The ending part of a word that modifies the meaning of the word.
Additional resources:   [Intro to med terms] [Med terms rules] [Med term reference] [Word building reference]  [Practice Exams]

Alphabetical Listing of Med Terms

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Medical Terminology Reference List- A

Medical terminology is used to precisely describe the human body components, processes, illnesses, medical procedures, and pharmacology. Medical terms are used in the field of medicine, and clinical settings. This section deals with med terms beginning with the letter "A", and features a list of Medical terminology is composed of a prefix, root word, and suffix.

Increasing your understanding of medical terminology

Additional references:

Word Building Reference- This resource strengthens your understanding of medical terminology. See how common medical terms are created using the various prefixes, suffixes, and root words.

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Medical Terminology Intuitive Section
This section was developed for 'speed learning' of medical terminology.

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a-   no; not; without
an-     no; not; without
ab-      away from
abdomin/o      abdomen
-ac      pertaining to
acanth/o       spiny; thorny
acar/o       mites
acetabul/o   acetabulum (hip socket)
acous/o       hearing
acoust/o       hearing, sound
acr/o        extremities; top; extreme point
acromi/o         acromion (extension of shoulder bone)
actin/o         light
acu/o      sharp; severe; sudden
-acusis       hearing
ad-       toward
-ad       toward
aden/o       gland
adenoid/o   adenoids
adip/o        fat
adren/o       adrenal gland
adrenal/o   adrenal gland
aer/o       air
af-       toward
agglutin/o   clumping; sticking together
-agogue      producer, leader
-agon       to assemble; gather
agora-       marketplace
-agra       excessive pain
-al       pertaining to
alb/o       white
albin/o       white
albumin/o   albumin (protein)
alges/o       sensitivity to pain
-algesia       sensitivity to pain
-algia       pain
all/o       other
alveol/o        alveolus; air sac; small sac
ambi-       around, on both sides, about
ambly/o       dim; dull
amphi-      around, on both sides
-amine       nitrogen compound
ammon/o        ammonium
amni/o      amnion (sac surrounding the embryo)
amyl/o       starch
an/o      anus
-an       pertaining to
ana-    up; apart; backward; again; anew
andr/o       male
aneurysm/o   aneurysm (widening of blood vessel)
angi/o       vessel (blood)
anis/o       unequal
ankyl/o       stiff
ante-       before; forward
anter/o       front
anthrac/o   coal
anthr/o       antrum of the stomach
anti-       against
anxi/o       uneasy; anxious
aort/o       aorta (largest artery)
-apheresis    removal
aphth/o        ulcer
apo-       off; away
aponeur/o   aponeurosis (type of tendon)
append/o       appendix
appendic/o   appendix
aque/o       water
-ar       pertaining to
arachn/o       spider
-arche       beginning
arsenic/o    arsenic
arter/o       artery
arteri/o       artery
arteriol/o   arteriole (small artery)
arthr/o      joint
-arthria       articulate (speak distinctly)
articul/o   joint
-artresia   closure, occlusion
atreto-       closed, lacking an opening
-ary       pertaining to
asbest/o       asbestos
-ase       enzyme
aspir/o      removal
-assay      to examine, analyze
-asthenia   lack of strength
astr/o       star, star-shaped
aque/o      water
atel/o       incomplete
ather/o      plaque (fatty substance)
-ation      process; condition
atri/o      atrium (upper heart chamber)
atmo-       steam, vapor
audi/o       hearing
audit/o       hearing
aur/o       ear
auricul/o   ear
auscult/o   to listen
aut/o       self; own
aut-       self; own
auto-       self; own
aux/o       growth, acceleration
axill/o       armpit
axi/o       axis
azot/o       urea; nitrogen


Check out the following resources to support your learning and understanding of medical terminology:

  • Quick Introduction- provides an overview and introduction to medical terminology.
  • Word Building Reference- This resource strengthens your understanding of medical terminology. See how common medical terms are created using the various prefixes, suffixes, and root words.
  • Medical Terms – rules governing singular versus plural versions of medical terms are described.
  • Medical Terminology Exams- twenty new exams were created to test your knowledge of medical terminology.


Word Building and Medical Terms beginning with the letter A



The belly, or the region of the body of a vertebrate between the thorax and the pelvis.  In human anatomy, the abdominal cavity (Abdominal = -abdomen/o = abdomen + -al = of the abdomen) is the largest cavity and holds the liver, gallbladder, spleen, stomach, pancreas, intestines, and kidneys.

  • Abdominal quadrants:

Anatomically, the abdomen is divided into four quadrants to help localize, identify, and diagnose abdominal pain or discomfort. The abdominal quadrants – left upper quadrant (LUQ), left lower quadrant (LLQ), right upper quadrant (RUQ), and right lower quadrant (RLQ) - are created by an imaginary horizontal (transumbilical) plane, and a median (mid-sagittal) plane.

  • Abdominal regions

The nine abdominal regions divide the abdomen into nine smaller sections.

  • Hypochondriac Regions (Left and Right): "Hypo" = below; "chondriac" = cartilage. This is the abdominal region under the ribs. Includes the gall bladder and the right lobe of the liver
  • Lumbar Regions (Left and Right): "lumbar" = vertebrae in the lower back. Portions of the small and large intestine and a part of the colon are included.
  • Inguinal (Iliac) Region (Left and Right): Beneath the lumbar region or top of the hip bone. The small intestine, the cecum, and portions of the colon are seen here.
  • Epigastric Region: "Epi" = above; "gastric" = stomach. Located between the left and right hypochondriac region, this is the region over and above the belly. Parts of the right and left lobes of the liver and a major portion of the stomach come under the epigastric region.
  • Umbilical Region: Between the right and left lumbar regions and directly beneath the epigastric region. Contains the navel, also called the umbilicus.
  • Hypogastric Region: "Hypo" = below. The region below the stomach or the umbilical region. Includes the urinary bladder, portions of the small intestine, and the appendix.
  • Abdominal ultrasound

Uses high-frequency sound waves to visualize the internal organs in the belly. The liver, gallbladder, bile ducts, pancreas, kidneys, bladder, and ureters, for example. This safe, non-invasive test is used to diagnose problems in the abdomen, such as pain, appendicitis, kidney stones, or abdominal aortic aneurysm.

  • Abdominocentesis

"abdomin/o = abdomen; -centesis =surgical puncture"

Also called the paracentesis, it involves removing excess fluid from the abdomen using a needle. The abdominal fluid may build up in relation to liver disease, heart failure, traumatic injury, tumors, ruptured intestines, or bladder.



acous/o = auditory or hearing; -tic = pertaining to

The term Acoustic means "having to do with or pertaining to sound or hearing".

Acoustic trauma – Damage or injury to the inner ear caused by exposure to a high-decibel noise. Over time, it leads to hearing loss.



The Greek-borrowed prefix means "thorn-like" characteristics, or "spiny-headed".

Acanthocephala ("acantha= spine, thorn or prickle; -cepahal/o = head") - a phylum of spine-headed worms including Acanthocephalus. They are intestinal parasites seen in vertebrates.

Acanthocyte ("acantha/o = spine; -cyte=vessel or hollow) - abnormal red blood cells with the spiked cell surface.

Acanthosis Nigricans - a skin disease with mole-like patches.




A combining form or prefix with the meaning "extremities", "top", and "height".

Acrochordon - Also called skin tag or fibroepithelial polyp, it is a benign, cutaneous growth. Most commonly appear on the neck, groin, eyelids, and inframammary regions.

Acrodermatitis (Acr/o = extremities; dermat = pertaining to skin; -itis = inflammation). In short, it is a skin condition that typically affects the extremities.

Acromegaly (acr/o = extremities; -megaly = enlarged) - A rare, slowly progressive hormonal disorder that happens when the pituitary gland overproduces growth hormone (GH). The most common symptom is the enlargement of the extremities, face, and/or jaw.

Acromion - A bony process on the superior end of the scapula.  It forms the highest point of the shoulder, to which the collarbone is attached.

Acroarthritis - Inflammation of hands and feet

Acroasphyxia - a disease characterized by compromised blood flow at the extremities

Acrophobia – Intense fear of heights



The rectangular mass of lymphoid tissues behind the nasal cavity, above the roof of the mouth. Also known as the pharyngeal tonsil or nasopharyngeal tonsil. They are part of the immune system, which helps fight infection and protects the body from pathogens.

Adenoidectomy – the surgical removal of adenoids.

Adenoiditis - Also called enlarged tonsils, it is the inflammation of the adenoids, often from bacterial or viral infection.





Of or relating to adrenal glands and their secretions. Also called the suprarenal glands, these are an inch or two long triangular glands located at the anterior end of each kidney. Each adrenal gland has two distinct parts: the outer adrenal cortex and the inner adrenal medulla. Both the adrenal cortex and adrenal medulla secrete distinct hormones.

  • Hormones of the adrenal cortex: Essential to life. They are Mineralocorticoids (Ex: aldosterone), Glucocorticoids (Ex: cortisol), and Adrenal androgens (Ex: dehydroepiandrosterone (DHEA) and testosterone).
  • Hormones of the adrenal medulla: Catecholamines (Ex: adrenaline, noradrenaline, and small amounts of dopamine). Medullary hormones aren’t necessary for life.

Adrenalectomy – surgical removal of one or both adrenal glands. Laparoscopic adrenalectomy is suggested when the adrenal glands are deceased or cancerous.



agglutin/o = "to clump or coalescence"

Agglutination - the act of uniting, the clumping of bacterial cells, red blood cells (RBC) by antibodies known as agglutinins.

Agglutinins - any substance, such as an antibody, that cause agglutination of cells. Agglutinins in the blood plasma play a vital role in blood typing. They make sure that there will be blood cells of only one blood type (A, B, AB, or O) in the circulation. If blood cells of a non-compatible blood type enter the body, agglutinins cause agglutination and induce blood cell destruction.

Agglutinogen - any foreign substance or antigen that induces the production of agglutinin.



Prefix referring to a gland. Related words:

Adenology - the study of glands

Adenocarcinoma – a form of cancer originating in glandular epithelium.  Gastric adenocarcinoma is one example, wherein the glandular epithelium of the gastric mucosa gets affected.

Adenohypophysis – the anterior glandular lobe that comprises 80% of the entire pituitary gland. The hormones secreted by adenohypophysis play a central role in regulating endocrine and behavioral functions, as well as being part of stress responses.

Adenovirus - a group of viruses that cause respiratory and gastrointestinal infections.

Adenoma – benign tumor of glandular tissue

Adenopathy - also referred to as lymphadenopathy, is the swelling of lymph nodes.


Adipose (Fat)

Fatty. Adipose cells also called adipocytes, lipocytes, or fat cells, are specialized to synthesize and store fat globules. Adipose is mainly a complex mixture of tripalmitin, tristearin, and triolein.

Adipose tissue is a specialized connective tissue made of adipocytes. It is seen under the skin (subcutaneous fat), around internal organs (visceral fat), between muscles, within the bone marrow, and in breast tissue. Based on morphology, adipose tissue is divided into two: white adipose tissue (in adults) and brown adipose tissue (in children).



A person with albinism. Albinism is a condition where a person is congenitally deficient in melanin pigment. Characterized by white hair, milky to translucent skin, and pink eyes with pink or blue iris and deep-red pupil.



The term alveolus refers to a hollow cavity, basin, trough, or bowl in Latin. Alveoli (plural) are the tiny air sacs that hold air in the lungs. Also known as pulmonary parenchyma, they are the structural and functional unit of the lung, where gaseous exchange takes place. The alveolar number is closely related to total lung volume, with larger lungs having as many as 700 million or so alveoli.



The prefix means blunt, dull, or dim.


A condition in which the eye and brain fail to work together, resulting in vision impairment in just one eye. Also called "lazy eye", amblyopia can occur in both eyes, which is rare.

Amblyopia starts in childhood, usually between ages 5 and 9 and it’s the most common cause of vision loss in kids. Refractive errors, strabismus (a condition where eyes are misaligned), clouding of the lens, intraocular tumor, or a corneal injury are some conditions that lead to amblyopia.

Treatment includes glasses, contacts, or surgery.



A gaseous mixture of hydrogen and nitrogen, NH3, colorless, water-soluble pungent compound. Also referred to as volatile alkali and spirits of hartshorn (aqueous solution of 28.5% ammonia). First recorded in 1790-1800. In 1782, Swedish chemist Torbern Bergman named the gas derived from sal ammoniac (smelling salts) deposits near the temple of Jupiter Ammon in Libya. Sal ammoniac is the natural mineralogical form of ammonium chloride.

Ammonia - An end-product of protein metabolism. The liver converts ammonia to urea, which the kidney excretes. In liver disease, the liver fails to clear ammonia, resulting in the accumulation of unmetabolized ammonia, a condition called hepatic encephalopathy.



The innermost extraembryonic membrane that surrounds the fetus and houses amniotic fluid. Amnion acts as a protective sac along with other extraembryonic membranes: chorion, yolk sac, and allantois.

Amniotic sac – a fluid-filled sac formed of amnion and chorion. The fetus grows inside this sac.

Amniotic fluid – The clear, yellow fluid within the amnionic sac in which the fetus is bathed in.  Amniotic fluid cushions the fetus against mechanical shock, allows movement, helps to prevent dehydration, and promotes skeletal development.  The amniotic fluid is released at childbirth when the amnion breaks.



Prefix indicating starch or polysaccharide.



A digestive enzyme secreted by the salivary glands (salivary amylase) and the pancreas (pancreatic amylase). Amylase digests carbohydrates in the food into glucose and maltose.   In a healthy adult, the normal amylase level is 56 to 190 IU/l.

Too high or too low amylase is an indication that the pancreas is diseased or inflamed. An amylase blood test is used to diagnose pancreatic disorders including pseudocyst, ulcer, cancer, or an abscess. The test is recommended in case of salivary gland infections, appendicitis, or ectopic pregnancy.

Amyloid (amylo- + -oid)

A waxy protein is found in the central nervous system (CNS). Plays a crucial role in neurodegenerative diseases like Alzheimer’s.



The excretory opening where the gastrointestinal tract (GIT) ends and exits the body. The rectum sits between the colon and anus and acts as a holding chamber for digestive wastes. When the pressure in the rectum is high, the anal sphincter muscles (an internal ring of muscles surrounding the anus) relaxes and aid in defecation.

The anus consists of glands, ducts, blood vessels, mucus, tissues, and nerves. Disorders of the anus include anal cancer, anal fissure, anal abscess, anal swelling, and anal fistula.


Prefix denoting male, man


Steroid hormones responsible for puberty, fertility, and sexual function in men. Though androgens are typically thought of as male hormones, the female body also produces them. The androgens produced in the ovaries and adrenal medulla are converted into estrogen, the female sex hormone.

Testosterone and androstenedione are the principal androgens. Other androgens include dihydrotestosterone (DHT), dehydroepiandrosterone (DHEA), and DHEA sulfate (DHEA-S).


Denoting aneurysm

Weakening or ballooning out of an artery wall. Although an aneurysm can occur in any part of the body, they’re most common in the brain (cerebral aneurysms), aorta (aortic aneurysms), legs (popliteal artery aneurysm), intestine (mesenteric artery aneurysm), and spleen (splenic artery aneurysm). In some cases, it is congenital. Aortic injury, high pressure, and high cholesterol may also cause an aneurysm.


Surgical removal of the ballooned portion of the affected area.


Prefix denoting blood vessels. 


The medical imaging technique used to visualize the vascular system. It is suggested when there are signs of a stroke or coronary heart disease. Angiogram also helps to understand and evaluate the restrictions in blood flow or damage to the blood vessel segments.


Prefix denoting stiffness, fixed or adhered.

Ankylosis - fused or stiffened joint

Ankylosing spondylitis

Also known as Marie-Strumpell disease or Bechterew’s disease, Ankylosing spondylitis (AS) is a type of inflammatory arthritis affecting the spine. AS often starts as a mild pain in the sacroiliac joints, eventually, the vertebrae fuse, resulting in spine stiffness or deformities.


Prefix denoting anterior or front.

Anteroposterior refers to direction or axis from front to the back, commonly associated with a chest radiograph.


Prefix denoting coal, carbon


An interstitial lung disease caused by inhalation of coal mine dust, smoke, or air pollution. Anthracosis can be seen as a superficial black discoloration of lung tissues (simple anthracosis) or scattered foci of dark spots (anthracotic lymphadenopathy)


Indicating antrum, a generic term for cavity or chamber. For example, the antrum of the stomach also called the pyloric antrum or gastric antrum. It is the lower portion of the stomach and contains numerous mucous- and gastrin-secreting cells.



Prefix indicating uneasiness or anxiety

Anxiety is when the body’s automatic fight-or-flight response gets triggered by a threat, pressure, challenges, or stress.

Anxiety disorders are the conditions in which the anxiety is constant, overwhelming, or recurring. Anxiety disorders are a group of related conditions, each having different symptoms in different individuals. Generalized anxiety disorder (GAD), panic attacks, Posttraumatic stress disorder (PTSD), and phobias, for example.


Of or related to aorta.

The largest artery in the body, begins at the left ventricle, extending upward into the chest to form the aortic arch. It then travels down into the abdomen, where it splits into the paired iliac arteries just above the pelvis.

Aorta carries oxygenated blood from the left ventricle to all parts of the body.


Suffix denoting taking away, withdrawal, or removal.

Hemapheresis is a medical procedure in which the components of blood - RBC, WBC, platelets, and plasma - are separated into layers using a Cell Separator machine. It is used to collect blood stem cells from donors and for treating a range of blood disorders including blood cancer.



Prefix denoting ulcer or lesions

Aphthous stomatitis 

Small painful sores recur on the tongue, gums, lips, or inside the cheeks; also called canker sores or aphthous ulcer.



Indicating aponeurosis.

The aponeurosis is a sheet-like fibrous connective tissue that anchors or connects a muscle to a bone or cartilage.



Indicating the vermiform appendix. The appendix is a 4-inch-long thin tube that sits where the small intestine meets the large intestine. Very little is known about its function and removing it is not harmful.


Painful swelling or inflammation of the appendix is caused by a bacterial infection.


Surgical removal of the inflamed or swollen appendix.


Prefix denoting spider or spider’s web.

Arachnoid mater - Named for its spider web-like appearance, the arachnoid mater is the middle layer of the three meninges that cover the brain and the spinal cord.

Arachnophobia - fear of spiders.


Of or related to arsenic. Arsenic is a greyish silver element which when ingested or inhaled causes arsenic poisoning, or arsenicosis. Long-term exposure to arsenic from contaminated food and water can cause cancer and skin lesions.


Pertaining to the artery. Arteries are the blood vessels that carry oxygenated blood away from the heart to the tissues.


Pertaining to the arteriole. Arterioles are the small diameter (<100 μm) blood vessels that connect arteries with capillaries. They are found all over the body and play a vital role in maintaining mean arterial pressure.


Combining form denoting joint

  • Arthropathy - Collective term for joint diseases.
  • Arthralgia - Joint pain arising from injury, infection, arthritis, and other ailments.
  • Arthritis - Joint inflammation. There are different types of arthritis. Osteoarthritis, Rheumatoid arthritis, Psoriatic arthritis, gout, lupus, and more.
  • Arthrocentesis - The clinical procedure that aspirates synovial fluid from a joint cavity for diagnostic purposes.
  • Arthrography - A musculoskeletal radiology test used to diagnose and treat arthropathies.
  • Arthroplasty - Joint replacement surgery


Suffix denoting articulation


Speech disorder caused by neurological damage to the muscles of speech. Speech may be strained, Jerky, breathy, irregular, or imprecise in people suffering dysarthria. Dysarthria can be developmental (brain damage during childbirth) or acquired (stroke, head injury, tumor, Parkinson's disease, or motor neuron defects).


Prefix denoting joints in the body.

Articular cartilage 

A layer of self-lubricating, white connective tissue that allows bones to glide smoothly against each other. Found only in the synovial joints, articular cartilage helps to absorb shock.


Absence of an orifice or passage in the body. Also indicates conditions where the opening in the body is closed.

Esophageal atresia 

A congenitally interrupted or malformed esophagus. This means the infants will have two esophagus parts - one connecting to the throat and another connecting to the stomach. Esophageal atresia is life-threatening if the two parts of the esophagus aren’t sewed together.


Suffix indicating an enzyme

  • Amylase - An enzyme that hydrolyses starch into sugars.
  • Lipase - Lipid digesting enzyme


Process of removal

Fine Needle Aspiration Biopsy

Aspirating tissue or fluid samples from muscles, bones, and other organs using a hollow needle. The samples thus collected are checked for infections or cancer.


Suffix indicating "to-examine", "to evaluate" or "to investigate"


An in vitro radiology test that measures the presence of antigen in the serum.

Enzyme-linked immunosorbent assay (ELISA) 

An immunological assay used to identify antibodies, proteins, peptides, and hormones. An ELISA test is used to diagnose HIV, rotavirus, pernicious anemia, and squamous cell carcinoma.


Suffix indicating lack or loss of strength, debility, or muscle weakness.

Myasthenia gravis (MG) 

A chronic autoimmune, neuromuscular disorder characterized by muscle weakness and fatigue. In this condition, the immune system mistakenly attacks acetylcholine receptors at the neuromuscular junction. This prevents the muscles from contracting and leads to muscle weakness.


Pertaining to star, star-like, or star-shaped


Star-shaped glial cells in the brain and spinal cord. Also known as astroglia, they play a vital role in supporting the blood-brain-barrier (BBB), nourishing the neurons, neurotransmission facilitation, and damage repair.


Tumour arising from astrocytes. In adults, about half of the primary brain tumors are astrocytomas.


Prefix indicating fatty plaque or soft fat deposit.


It is the plaque buildup in the inner lining of an artery. Fat, cholesterol, calcium, and inflammatory cells are the common materials that adhere to arteries.


ather/o = fatty; sclero = hardening; -osis= condition. A condition caused by atheroma and characterized by narrowed arteries.


Combining form indicating atria (atrium - singular), the upper two heart chambers. Each atrium - right atrium and left atrium - empty blood returning to the heart into the corresponding ventricle.

Atrial fibrillation 

Atrial fibrillation happens when atria and ventricles don’t work together as they should due to faulty electrical signaling, resulting in quivering or irregular heartbeats.

Atrial flutter (AFL)

A condition in which atria beat faster than the ventricles. The atrial rate in AFL is 250 - 400 beats per minute.

Atrioventricular node (AV node)

The electrical gatekeeper that slows down the cardiac impulse propagation between the atria and the ventricles. In the case of the sinoatrial node (SA node) dysfunction or advanced atrioventricular (AV) block, the AV node acts as an intrinsic pacemaker.


Prefix indicating "to hear" or "to listen"


A noninvasive hearing test that measures how well one can hear.


Shows the softest sounds one can hear at different frequencies. In other words, it is the graphical representation of one’s hearing ability. The audiologist uses audiograms to identify whether a person has hearing loss, and determine the degree of impairment if the results are positive.


Science of hearing, balance, and associated disorders.


Prefix meaning ear.


Outer ear or pinna. The auricle amplifies sound waves and funnels them towards the inner ear. Cauliflower ear, also known as perichondrial hematoma or wrestler's ear, is a deformity of the auricle caused by an injury.


Combining form meaning "to listen". From Latin auscultare.


A diagnostic procedure involving listening to sounds of thoracic or abdominal viscera. Abnormal sounds could indicate problems in the lungs, heart valves, and abdomen.


Prefix borrowed from Latin ala meaning "wing" "armpit", "hollow or cavity under the arm".


Also known as the armpit, the axilla is the concave area marking the upper limb and thorax. The axilla is the passageway for several neuromuscular structures, axillary lymph nodes, axillary artery and vein, and the brachial plexus.

Axillary temperature 

The temperature obtained by placing the thermometer in the armpit. It is commonly used in infants and young children. The axillary temperature may be as much as 1-degree Celsius less than the oral temperature.


Prefix indicating nitrogen.


Elevation, or buildup of urea or other nitrogenous wastes such as creatinine in the blood as a result of renal insufficiency. Diabetes, congestive heart failure, renal disorders, chronic diarrhea, or vomiting are some conditions that reduce blood flow to the kidney and damage organ function.

Medical Terminology Reference List- A