Definitions for common medical terms

These medical definitions are courtesy of the Medical Library Association's Medspeak website (copyright 2003). Use the alphabetical index below to look up a term.

A . B . C . D . E . F . G . H . I . J . K . L . M
N . O . P . Q . R . S . T . U . V . W . X . Y . Z

ACE INHIBITORS — Angiotensin Converting Enzyme Inhibitors, a class of drugs used in the treatment of heart disease to help keep blood vessels dilated (open) to improve blood flow

ACUTE — condition that requires immediate medical attention

ADJUNCT — a necessary addition to a diagnostic or treatment process

AIDS — Acquired Immune Deficiency Syndrome, a disease in which the body's immune system loses the ability to fight off infections

ALGIA — when used as part of word, means pain or ache, e.g. myalgia or muscle pain

ALLERGY — over-reaction by the immune system to substances that are normally harmless such as dust, animal hairs, certain foods or pollen

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–B–

BACTERIA — one-celled microorganisms found in soil, water and air, some of which cause infectious disease in humans and animals

BASAL METABOLIC RATE — a measurement of thyroid function via a breathing test that measures oxygen used and calories spent while at rest

BENIGN — noncancerous

BETA BLOCKERS — drugs often used to treat hypertension to reduce the rate and force of the heart beat

BRACHI, BRACHIO — prefix indicating a connection to the arm

BRADY — prefix meaning slow, e.g. bradycardia or slow heart beat; bradylalia, slow speech

BRONCHI, BRONCHO — when used as part of a word, refers to the passages that lead to the lungs, e.g. bronchitis, inflammation of the bronchial passages

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–C–

CARCIN — when used as part of a word, means cancer, e.g., carcinogen, a substance known to cause cancer

CARDIO — when used as part of a word, refers to the heart

CENTESIS — puncture with a hollow needle to draw fluid

CHD — Coronary Heart Disease

CHROMOSOME — a threadlike structure in every cell that carries genetic codes

CHRONIC — condition or disease that can be controlled but not cured, e.g., asthma, diabetes

CYST — closed, fluid-filled, or semisolid sac embedded in the tissue

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–D–

DECRUDESCENC — lessening of the severity of symptoms

DEGENERATIVE DISORDER — conditions characterized by deterioration of body parts that worsen over time, such as arthritis or muscular dystrophy

DERM, DERMA — when used as part of a word, means skin

DIAGNOSIS — identifying a disease or condition by examining the patient's history, symptoms, appearance, and, if necessary, analysis of diagnostic tests

DIFFERENTIAL DIAGNOSIS — is a list of the different diseases that can cause these symptoms

DIS — when used as a part of a word means removal or reversal, e.g., disability or dislocate

DYS — when used as a part of a word, means difficulty, e.g., dysarthria, difficulty in speaking; dyslexia, difficulty reading because some letters appear in reverse order

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–E–

ECTO — when used as a part of a word, means outside

-ECTOMY — suffix meaning surgical removal, e.g., appendectomy, surgical removal of the appendix

EDEMA — abnormal accumulation of fluid in the cells especially just under the skin or in an organ such as the heart. Causes include allergy, disease, or injury.

EEG — Electroencephalogram, a diagnostic test used to measure the brain's electrical activity

EKG or ECG — Electrocardiogram, a diagnostic test used to measure the heart's electrical activity

ELECTRO — when used as a part of a word, means electricity

ELECTROLYTE — chemical substance found in the body, including calcium, potassium and sodium, that produces an electrical charge and is vital for maintaining good health

EMBOLISM — blockage of a blood vessel by a blood clot, a piece of tissue, an air bubble, or a foreign object

ENDO — when used as a part of a word, means inward

ENDOCRINE GLANDS — hormone-producing glands that regulate the body's normal function

EP, EPI — when used as a part of a word, means above

EPIDERMIS — outer layer of the skin that contains nerve endings but no blood vessels

EXOCRINE GLANDS — glands, including sweat glands, tear ducts, and salivary glands, that regulate normal body functions through external secretions

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–F–

FASCIA — fibrous connective tissues that supports soft organs and covers muscle tissue

FAT METABOLISM — conversion of fatty foods into energy used by cells in the body

FIBERODENOMA — benign, firm, moveable tumor of the breast

FONTANEL — the two "soft spots" found in an infants skull. The fontanel usually close by 18-24 months of age.

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–G–

GASTRI, GASTRO — when used as a part of a word, refers to the stomach or abdomen, e.g., gastritis, an inflammation of the stomach's lining

GENE — basic unit of a chromosome that determines hereditary information such as eye color

-GENESIS — suffix meaning "produced," e.g., pathogenesis, disease producing

GI SERIES — usually a group of x-ray tests or the digestive of gastrointestinal system

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–H–

HEM, HEMA, HEMO — when used as part of a word, means blood, e.g., hemangioma

HYPER — prefix meaning excessive, above, or beyond, e.g., hyperactive

HYPO — prefix, meaning deficient, under, or below, e.g., hypoglycemia or lower-than-normal level of glucose in the blood

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–I–

IMMUNE RESPONSE — the body's defense against antigens (substances such as bacteria and viruses) that the body recognizes as foreign and creates antibodies to destroy. The immune response can also be triggered by non-harmful substances. See allergy

INDOLENT — slow in growth or development accompanied by little or no pain

INTRA — prefix meaning within, e.g., intracranial, within the head or skull

IN VITRO — occurring in laboratory apparatus (glassware): this means an experiment not in a living human or animal

IN VIVO — in a living organism

ISCHEMIA — decreased supply of oxygenated blood to any part of the body

-ITIS — suffix meaning inflammation

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–J–

JUXTA — when used as part of a word, means "near," e.g. juxtacardia, near the heart

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–K–

KELOID — excessive growth of scar tissue

KETONE BODIES — substances produced by the normal breakdown of fats in the body; abnormal amounts of ketone bodies in the blood (ketoanemia) or urine (ketonuria) are an indication of uncontrolled diabetes mellitus or starvation

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–L–

LACTASE — a substance secreted by glands in the small intestine that break down lactose (milk sugars) into simpler sugars. Lactose intolerance is the body's inability to digest lactose normally.

LALTO, LALO — when used as part of a word, refers to speech

LIGAMENT — shiny band of connective tissue that binds joints and connects bones and cartilage; similar to "tendon" which connects muscles to bone

LIPO — when used as part of a word, refers to body fat

LYMPH — thin fluid containing lymphocytes produced by lymph nodes that circulates through the lymph vessels

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–M–

MALIGNANT — tending to become worse or invasive

MEMBRANE — a thin layer of tissue that lines or covers a part of the body, e.g. nasal membrane

METASTASIS — cancer cells migrating to spots outside the original cancer

MI — Myocardial Infarction, commonly called "heart attack," describes damage to heart muscle caused by decreased blood flow

MINOR SURGERY — any surgical procedure performed without general anesthesia

MONO — only, sole

MY, MYO — when used as part of a word, refers to muscle, e.g. myalgia, muscle pain, or myasthenia, abnormal muscle weakness

MYELIN — protective sheath encasing nerve fibers

MYOPIA — literally "weak eyes" or nearsightedness

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–N–

NASO — when used as a part of a word, refers to the nose

NEONATE — infant from birth to four weeks in age

NEPHR, NEPHRO — when used as part of a word, refers to the kidneys, e.g., nephrectomy, surgical removal of a kidney

NEURO — when used as part of a word, refers to the nervous system, including the brain

NONINVASIVE — any medical technique that does not involve puncturing or entering the body

NOSO — when used as part of a word, means disease, e.g., nosocomial

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–O–

ONCO — when used as a part of a word, means a tumor or mass, e.g., oncologist, one who specializes in tumors

-OMA — tumor

-OSIS — suffix indicating a condition, especially disease

OSTEO — when used as part of a word, means bone, e.g., osteoporosis, a condition characterized by porous or fragile bone.

OTITIS — an inflammation of the ear; otitis media is an inflammation of the middle ear

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–P–

PALPATION — diagnostic technique of feeling, with the hands, the firmness, texture, or location of various body parts

PALPITATION — pounding or racing of the heart

PARENTERAL — administration of a drug by injection or through any means other than the digestive system, e.g., parenteral nutrition means feeding the patient through a tube inserted into the veins

PERI — when used as a part of a word, means around, e.g., pericardial sac, a protective sac around the heart

PERTUSSIS — acute, contagious respiratory disease usually found in young children, also called whooping cough

PHLEBO — when used as a part of a word, refers to veins

-PLEGIA — when used as a part of a word, means paralysis

POST — after or later, e.g., postmortem (after death)

PRURITUS — itching

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–Q–

QUARANTINE — isolation of people with contagious disease in an effort to prevent the spread of disease

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–R–

RACHI, RACHIO — when used as the part of a word, means the spine

REFLEX — involuntary movement in response to certain stimulus

RENAL FAILURE — inability of the kidneys to function and remove waste

RSV — Respiratory Syncytial Virus, any group of viruses that cause respiratory disease in children or adults including Respiratory Distress Syndrome in newborns

RETICULUM — network

RHINITIS — inflammation of the nasal membranes usually caused by allergies or the common cold

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–S–

SANGUI , SANGUIO — when used as part of a word, refers to blood

SARCO — when used as a part of a word, refers to flesh

SCHIZO — when used as a part of a word, means division or split

SCLER, SCLERO — when used as a part of a word, means hard, e.g., scleroderma, hardening of the skin

SEPSIS — infection or contamination, e.g., asepsis, which means sterile or uncontaminated

STATIC — unchanging

SUB — when used as a part of a word, means under, e.g., sublingual, under the tongue

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–T–

TACHY — when used as a part of a word, means swift or rapid, e.g., tachycardia, abnormally fast heartbeat

THERMO — when used as a part of a word, refers to heat, e.g., thermometer, a device for measuring temperature

THROMBO — when used as a part of a word, refers to a blood clot, e.g., thromboectomy, surgical removal of a blood clot

TISSUE — a collection of similar cells acting together to perform a particular function

TOPICAL — surface, e.g., topical ointment is applied to the skin

TRANS — when used as part of a word, means across, through, or over

TRICHI, TRICHO, TRICHIA, TRICHOSIS — when used as a part of a word, refers to hair

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–U–

ULCER — sore of lesion of the skin or membrane of an organ caused by infection or disease

URO, URONO — when used as a part of a word, refers to urine, the urinary tract, or urination

UTER, UTERO — when used as a part of a word, refers to the uterus

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–V–

VACCINE — substance made from a weakened or dead virus or bacteria, which is administered orally or by injection to trigger the body's immune defense. Polio and smallpox are two diseases that are nearly extinct in the U.S. because most of the population have taken vaccines to protect them against these diseases

VALVE — structures, usually a flap of tissue, found in the heart, veins, lymph vessels, and other passages that ensure fluid contents, like blood, flow in only one direction

VIRUS — a micro-organism that must attach itself to a living cell to complete itself and be able to reproduce. Some viruses are disease-producing and causes illnesses such as measles, chickenpox, some types of pneumonia, and the common cold.

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–W–

WHEEZE — a high-pitched sound that indicates a narrowed airway. Usually caused by chronic respiratory disease such as asthma but can also be caused by a foreign object in the airway.

WITHDRAWAL SYMPTOMS — physical changes that result when addictive substances such as nicotine, alcohol, or narcotics are removed. Withdrawal symptoms are sometimes life-threatening.

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–X–

X CHROMOSOME — determines gender; females have two X chromosomes and males have one X and one Y chromosome

XENO — when used as a part of a word, means strange or foreign

XER, XERO — when used as part of a word, means dryness, e.g., xerocheilia, dry lips

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–Y–

Y CHROMOSOME — part of the genetic code that is found only in males

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–Z–

ZOO — when used as a part of a word, refers to animals, e.g., zoonosis, a disease such as rabies that is transmitted by animals to humans

ZYGOMATIC — the cheekbones

ZYGOTE — a fertilized egg

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