Medical terms A–Z

A judgment about right and wrong conduct, which in health care sits alongside law and professional rules rather than inside them.

A disease or the incidence of disease within a population.

A tropical shrub.

Shape treated as evidence: what a cell, an organ or a whole organism looks like, before asking what it does or is made of.

As a medical descriptor, motor relates to muscle movement or to the nerves and brain regions directing it, as in motor neuron or motor cortex.

The use of special strains of mice to study a human disease or condition, and how to prevent and treat it.

Burning a dried herb at or above the skin to heat a chosen point, a practice defined by warmth where acupuncture is defined by needles.

Moxifloxacin is a broad spectrum antibiotic from the fluoroquinolone class, used to treat various bacterial infections.

A substance being studied in the treatment of several types of cancer.

No x-rays are involved, which is one reason this scan is used so heavily in neurology, orthopedics and pediatric imaging.

Measuring how much of it a cell holds is the standard way to judge whether a particular gene is switched on or off.

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

A substance that is being studied in the treatment of cancers of the blood.

MSI marks a defect in a cell's DNA repair machinery, seen as changes in short repeated DNA sequences, most notably in colorectal and endometrial tumors.

A ceiling found by pushing upward until harm appears, which suits chemotherapy and fits modern targeted drugs poorly.

The cell's growth switch, wired to read food, energy and hormone signals before deciding whether building is affordable.

A drug used to treat some types of cancer, rheumatoid arthritis, and severe skin conditions, such as psoriasis.

A substance found on certain epithelial cells (cells that cover organs, glands, and other body surfaces) and on breast cells involved in making milk.

A protein/sugar compound made by some cancer cells.

A pathologist's word for tissue that looks and feels like jelly, because its cells are pouring out the protein that thickens mucus.

A type of cancer that begins in cells that line certain internal organs and produce mucin (the main component of mucus).

Mucosa is the moist membrane lining internal passages and cavities such as the mouth, gut, and airways, often producing protective mucus.

Mucositis most often affects the lining of the mouth and digestive tract, commonly appearing as painful sores following certain cancer treatments.

The moist, inner lining of some organs and body cavities (such as the nose, mouth, lungs, and stomach).

Mucus is a viscous, protective fluid that coats and moistens internal surfaces, trapping particles and helping shield the tissue beneath it.

A type of monoclonal antibody used in cancer detection or therapy.

A rare cancer of the uterus, ovary, or fallopian tubes.

A clinical trial that is carried out at more than one medical institution.

Breast cancer in which there is more than one tumor, all of which have formed separately from one another.

In medicine, a term used to describe a treatment planning approach or team that includes a number of doctors and other health care professionals who are experts in different specialties (disciplines).

A treatment planning approach in which a number of doctors who are experts in different specialties (disciplines) review and discuss the medical condition and treatment options of a patient.

Adaptation of tumor cells to anticancer drugs in ways that make the drugs less effective.

Treatment used to make cancer cells less resistant to anticancer drugs.

Breast cancer in which there is more than one tumor, all of which have arisen from one original tumor.

Therapy that combines more than one method of treatment.

A rare, inherited disorder that affects the endocrine glands and can cause tumors in the parathyroid and pituitary glands and the pancreas.

A rare, inherited disorder that affects the endocrine glands and can cause tumors in the parathyroid and pituitary glands and the pancreas.

An inherited disorder marked by the formation of many noncancerous growths called hamartomas.

Harm arrives from two directions at once: cells crowding the marrow, and the abnormal protein those cells pour into the circulation.

Scattered patches of damage explain the scattered symptoms, since what a person notices depends entirely on which pathway has been hit.

Multiplicity describes the presence of more than one instance of a finding, such as several tumors or lesions, within the same patient or organ.

A small green legume better known as a sprout, and one of many foods given cancer claims that its nutrition does not support.

A drug being studied in the treatment of young adults with bone cancer that has gotten worse or come back.

Muscle shrinking because it is not being used, not being fed, or is being broken down faster than the body rebuilds it.

Bone alone cannot move and muscle alone cannot hold shape, which is why the two are named, examined and treated as one system.

Music therapy is a credentialed clinical practice using structured musical activities, guided by a trained therapist, to address physical, emotional, or cognitive treatment goals.

A drug used to treat some types of cancer and some skin conditions that may become cancer.

A mutagen is any physical or chemical agent capable of altering a cell's DNA, with ultraviolet light and certain chemicals among the most familiar examples.

To change the genetic material of a cell.

Any change in the DNA of a cell.

A person who has a mutated (changed) copy of a gene.

Whether the ache sits in one muscle or everywhere at once is the first question, because the two lists of causes barely overlap.

Despite a name suggesting fungal origin, mycosis fungoides is the most common form of cutaneous T-cell lymphoma, a cancer of white blood cells.

In mycosis fungoides, an area of skin that is thickened, raised, red, scaly, and itchy.

A drug used to treat infections caused by fungi (a type of microorganism).

Myelin is a fatty insulating layer wrapped around nerve fibers that speeds electrical signaling and protects the underlying nerve from damage.

A severe form of myelosuppression.

High-dose chemotherapy that kills cells in the bone marrow, including cancer cells.

Refers to myeloblasts (a type of immature cell that forms in the bone marrow).

The marrow is busy but unproductive, making faulty cells that die before reaching the blood, so counts fall while the marrow stays crowded.

Scar tissue crowds out the marrow, so blood cell production migrates to the spleen and liver, which swell as they take over.

Myelogenous describes anything arising from or resembling bone marrow and is often used interchangeably with myeloid when naming certain leukemias.

An x-ray of the spinal cord after an injection of dye into the space between the lining of the spinal cord and brain.

One of the two great branches of blood cell production, and the branch that supplies everything except lymphocytes.

One plasma cell clone takes over the marrow and floods the blood with a single useless antibody, damaging bone and kidneys as it grows.

A type of cancer that begins in plasma cells (white blood cells that produce antibodies).

An abnormal type of white blood cell that is found in chronic myelomonocytic leukemia.

These conditions are grouped by overproduction of blood cells, setting them apart from disorders in which the marrow instead fails to produce enough.

A progressive, chronic disease in which the bone marrow is replaced by fibrous tissue and blood is made in organs such as the liver and the spleen, instead of in the bone marrow.

Myelosuppression is reduced bone marrow activity that lowers red blood cell, white blood cell, and platelet counts, commonly following chemotherapy or radiation.

Treatment that inhibits blood cell production.

The formal name pins down what the everyday phrase leaves vague: a patch of heart muscle killed by blood flow that stopped.

A myoclonic jerk can occur normally, such as while falling asleep, or as a sign of an underlying neurological condition.

Myoinositol is a sugar alcohol the body makes and obtains from food, often marketed as vitamin B8 despite not meeting the definition of a vitamin.

The myometrium is the thick muscular wall of the uterus that contracts during labor and menstruation and gives the organ its structural strength.

A substance being studied in the prevention of skin cancer.

The antidote that makes an acetaminophen overdose survivable, by refilling the liver's supply of a protective molecule the drug has burned through.

This medication thins mucus for easier clearance and serves as the standard antidote for dangerous acetaminophen overdose by replenishing a key liver antioxidant.

A substance that is being studied as an anticancer drug in the treatment of non-small cell lung cancer.

A substance that is being studied in the treatment of leukemia.

A substance that is used in cancer research to cause bladder tumors in laboratory animals.

Sodium chloride, written NaCl, is an essential electrolyte used medically in intravenous fluids, saline solutions, and wound irrigation.

One of the few drugs that does nothing at all unless a particular poison is present, which is what makes it usable by bystanders.

Blocking rather than replacing sets it apart from methadone and buprenorphine, and it is why timing after withdrawal matters so much.

A billionth of a gram, the scale at which hormones and drug levels in the blood are actually measured.

The scale on which molecules, viruses and wavelengths of light are measured, far below anything an ordinary microscope can resolve.

The amount of a substance equal to a billionth of a mole (a measure of the amount of a substance).

Small enough that surface area dominates behavior, which is why the same material acts differently once broken this fine.

A drug used to treat breast cancer that has spread or that has come back within 6 months after chemotherapy.

A device that uses x-rays instead of visible light to form images of very small structures, such as the insides of blood vessels and cells.

Nanotechnology engineers materials at the scale of individual atoms and molecules, with applications spanning electronics, materials science, and medicine.

The legal meaning and the medical one no longer match, and some drug laws classify cocaine as a narcotic though it is not an opioid.

Nasal structures and treatments involve the nose and nasal passages, which warm, filter, and humidify air on its way to the lungs.

Describes the passage from the nose to the stomach.

A soft tube threaded through the nose down into the stomach, used to feed, to give medicine, or to drain.

A steroid aimed at one surface: the same molecule is sold as a cream and an inhaler, but under different names entirely.

Nasopharyngeal cancer arises in the upper throat behind the nose and is strongly linked to Epstein-Barr virus infection.

The nasopharynx is the uppermost part of the throat, connecting the nasal cavity to the rest of the airway and to each middle ear.

A thin tube-like instrument used to examine the inside of the nose.

Examination of the inside of the nose using a nasoscope (or rhinoscope).