Medical terms A–Z

A federal agency that uses science to explore complementary and alternative medicine (CAM) practices, trains CAM researchers, and provides authoritative information about CAM to professionals and…

A federal agency in the U.S.

A study that follows a group of people over time who have, or are at risk of developing, a specific medical condition or disease.

Natural killer cells are innate immune cells that destroy virus infected and abnormal cells without needing prior exposure to a specific target.

A whole system rather than a single treatment, built on the premise that the body heals itself once the obstacles are removed.

Nausea is an uncomfortable stomach sensation often preceding vomiting, with causes ranging from motion and illness to medication and pregnancy.

A substance that is being studied for its ability to make cancer cells respond to drugs to which they have become resistant.

A substance being studied in the treatment of cancer.

A federal agency that uses science to explore complementary and alternative medicine (CAM) practices, trains CAM researchers, and provides authoritative information about CAM to professionals and…

This abbreviation identifies the primary United States federal agency responsible for conducting and funding cancer research, training, and public health information.

A substance being studied in the prevention of colorectal cancer.

A drug put on the skin to treat growths caused by sun exposure.

A nebulizer converts liquid medication into a fine mist that a person inhales directly into the lungs and airways.

Surgery to remove lymph nodes and other tissues in the neck.

Cells dying by accident spill their contents and inflame the area around them, unlike the body's orderly disposal of unwanted cells.

The removal of tissue or fluid with a needle for examination under a microscope.

A procedure used to mark a small area of abnormal tissue so it can be removed by surgery.

A procedure to mark and remove abnormal tissue when the doctor cannot feel a lump.

A procedure used to mark a small area of abnormal tissue so it can be removed by surgery.

The part of acupuncture that can actually be observed, which is why research keeps circling back to it rather than to the theory.

An antidepressant kept in limited use because of a rare but severe effect on the liver.

A lymph node in the armpit that is free of cancer.

A test result that does not show the specific disease, condition, or biomarker for which the test is being done.

Treatment moved to the front of the queue, shrinking a tumor before surgery and revealing in advance how it answers back.

Neoplasia is the process of abnormal cell growth that forms a new, uncontrolled mass of tissue, which may be benign or malignant.

A neoplasm is an abnormal tissue growth from uncontrolled cell division, encompassing both benign growths and malignant cancers rather than cancer alone.

A serious problem that may occur in cancer in which cancer cells spread from the original (primary) tumor to the meninges (thin layers of tissue that cover and protect the brain and spinal cord).

A nephrectomy is surgery to remove all or part of a kidney, performed through several different approaches depending on how much tissue must be removed.

Not one disease but a family of them, sharing inflamed kidney tissue and a set of clues that appear in the urine.

A physician for the kidney as a chemical regulator rather than as a piece of plumbing, which is where the surgeon takes over.

Pressure rather than pain is the danger, since urine that cannot escape backs up and injures the kidney quickly.

A series of x-rays of the kidneys.

Nephrotoxic describes a substance capable of damaging the kidneys, a property considered when prescribing certain medications or evaluating toxic exposures.

Surgery to remove a kidney and its ureter.

A nerve is a bundle of fibers carrying electrical and chemical signals between the brain, spinal cord, and the rest of the body.

A procedure in which medicine is injected directly into or around a nerve or into the spine to block pain.

Every thought, movement and sensation depends on these cells passing electrical and chemical signals to one another.

Replacing a damaged nerve with a section of a healthy nerve that has been removed from another part of the body.

A survival signal made by the tissue rather than by the nerve, which is how the body matches nerve supply to what needs supplying.

A type of surgery that attempts to save the nerves near the tissues being removed.

Most of what it does never reaches awareness, since heartbeat, digestion and blood vessel tone are governed with no conscious involvement at all.

NES applies small electrical impulses to weak or paralyzed muscles to help maintain strength, circulation, and range of motion.

The all-purpose adjective for anything to do with nerves, and one that quietly differs from neuronal in what it takes in.

Pain with no injury underneath it, which is why ordinary painkillers disappoint and drugs built for epilepsy and depression do not.

A doctor who specializes in diagnosing and treating brain tumors and other tumors of the nervous system.

The bridge word between neurology and psychiatry, covering changes in conduct and mood that trace back to the brain itself.

Neuroblastoma is a cancer of immature nerve cells that develops mainly in infants and young children, often starting near the adrenal gland.

Having to do with the ability to think and reason.

A tumor of the central or peripheral nervous system.

Describing the crossover point at which a nerve impulse ends in a hormone released into the blood rather than a message to the next cell.

Neuroendocrine tumors arise from hormone releasing cells scattered throughout the body and can secrete excess hormones causing varied symptoms.

Having to do with tissue made up of sensory cells, such as tissue found in the ear, nose, and tongue.

A benign tumor that develops from the cells and tissues that cover nerves.

Neuroglia are the supportive cells of the nervous system that surround, nourish, and protect nerve cells rather than transmitting signals themselves.

A type of drug used to treat symptoms of psychosis.

A life-threatening condition that may be caused by certain drugs used to treat mental illness, nausea, or vomiting.

A pointer to a system rather than a diagnosis, and one that narrows the search only once the examination localizes the problem.

A doctor who specializes in the diagnosis and treatment of disorders of the nervous system.

A neuroma is a benign growth composed of nerve tissue that can develop after nerve injury or arise along an existing nerve pathway.

The cell behind every thought and every movement, and the one the adult brain almost never replaces once it is lost.

A doctor who never meets the patient, yet whose reading of a few slides can settle a diagnosis nothing else can settle.

Disease or dysfunction of one or more nerves.

Short protein-like messengers used by nerve cells for slower, longer-lasting signals than ordinary neurotransmitters send.

A scan shows structure, while neuropsychological testing shows what a person can actually do, and the two often disagree.

Neuroradiologists interpret imaging of the brain, spine, and nervous system and often perform minimally invasive procedures guided by those same images.

A doctor who specializes in surgery on the brain, spine, and other parts of the nervous system.

Neurotoxicity refers to damage to nerve tissue caused by exposure to a toxic substance, whether a chemical, drug, or naturally occurring toxin.

A neurotoxin is a substance that damages or disrupts the normal function of nerve cells or the nervous system.

Neurotransmitters are chemical messengers released by nerve cells to relay signals across the small gaps separating one nerve cell from another or from a muscle.

An ability to invade and live in neural tissue.

A condition in which there is a lower-than-normal number of neutrophils (a type of white blood cell).

Short lived by design: these cells are produced in vast numbers, survive briefly and die where they fight, which is what pus is.

A nevus, more commonly called a mole, is a benign cluster of pigment producing skin cells that can be flat or slightly raised.

A rare genetic condition that causes brown spots and tumors on the skin, freckling in skin areas not exposed to the sun, tumors on the nerves, and developmental changes in the nervous system…

A genetic condition in which tumors form on the nerves of the inner ear and cause loss of hearing and balance.

The abbreviation written on charts for the nose-to-stomach tube, and the one most often confused with the other tubes on a ward.

Nicotinamide is a form of vitamin B3 that the body needs for energy production, distinct from niacin in that it does not cause flushing.

Nicotine gum is an over the counter chewing gum that delivers a measured dose of nicotine to ease cravings during smoking cessation.

A device used to inhale (breathe in) small doses of nicotine through the mouth.

A hard candy-like tablet that contains a small dose of nicotine.

A nose spray that contains a small dose of nicotine, which enters the blood by being absorbed through the lining of the nose.

A nicotine patch delivers a steady, low dose of nicotine through the skin, easing withdrawal symptoms for someone reducing or stopping tobacco use.

A type of treatment that uses special products to give small, steady doses of nicotine to help stop cravings and relieve symptoms that occur when a person is trying to quit smoking.

A nutrient in the vitamin B complex that the body needs in small amounts to function and stay healthy.

Most of what this agency does happens somewhere else, in laboratories it pays for rather than laboratories it owns.

The raised opening at the center of the breast where the milk ducts reach the surface, ringed by darker skin.

Fluid that is not milk coming from the nipple.

Nitric acid is a strong, corrosive industrial chemical, distinct from nitric oxide, the body's own blood vessel signaling molecule.

An alkaloid drug belonging to a class of anticancer agents called topoisomerase inhibitors.

Chemicals that assemble wherever nitrite meets the right partner, including inside the stomach, and that damage DNA once the liver has processed them.

An anticancer drug that can cross the blood-brain barrier.

An NK cell is a white blood cell of the innate immune system able to kill infected or abnormal cells on first contact.

A type of immune cell that has granules (small particles) with enzymes that can kill tumor cells or cells infected with a virus.

A type of leukemia in which large natural killer (NK) cells (a type of white blood cell) that contain granules (small particles) are found in the blood.

A type of leukemia in which large natural killer (NK) cells (a type of white blood cell) that contain granules (small particles) are found in the blood.

A rare type of Hodgkin lymphoma, which is a cancer of the immune system.

A smaller number means a stronger compound, since less of it is needed to produce the same effect.

Electrical pulses that make a muscle work when the brain's own signal is too weak or cannot get through.

Cancer that has not spread to the lymph nodes.

Cancer that has spread to the lymph nodes.