Medical terms A–Z

Diet refers both to everything a person routinely eats and drinks and to a specific eating pattern prescribed for a medical condition.

A process by which a health professional with special training in nutrition helps people make healthy food choices and form healthy eating habits.

A detailed diet plan that states what, how, and when a person will eat and drink.

Not one number per nutrient but several, each answering a different question, from an average requirement to the level where risk begins.

Taken by mouth to add to regular food, these products supply concentrated nutrients such as vitamins, minerals, herbs, or amino acids.

The protected title is the practical difference, since anyone may call themselves a nutritionist while dietitian carries a defined training route behind it.

Differentiation is the process by which unspecialized cells develop into distinct, mature cell types suited to specific functions in the body.

Diffuse describes a finding, symptom, or process that is spread broadly through a tissue or region rather than confined to one specific area.

A childhood condition in which abnormal tissue grows on the outer part of one or both kidneys.

A type of central nervous system tumor that forms from glial (supportive) tissue of the brain and spinal cord.

A type of B-cell non-Hodgkin lymphoma (cancer of the immune system) that is usually aggressive (fast-growing).

A substance being studied in the treatment of cancer.

Digestion mechanically and chemically converts food into absorbable nutrients through the coordinated action of the mouth, stomach, intestines, and accessory digestive organs.

The digestive system is a continuous tract of organs, aided by the liver and pancreas, breaking food into nutrients the body can absorb and use.

A single tube open at both ends, so its contents count as outside the body until they cross the lining.

A method in which an image or other type of data is changed into a series of dots or numbers so that it can be viewed and studied on a computer.

The use of a computer, rather than x-ray film, to create a picture of the breast.

Capturing images on a sensor instead of film, which is what made routine clinical photography and remote review practical.

A garden flower that became a heart drug, still in use after two centuries, with a famously narrow margin for error.

Used in photodynamic therapy, a drug that is absorbed by tumor cells; when exposed to light, it becomes active and kills the cancer cells.

A long established seizure medicine whose blood level climbs unpredictably with dose, which is why it is measured rather than assumed.

A procedure to remove tissue from the cervical canal or the inner lining of the uterus.

The same word covers a vessel relaxing on its own, a pupil widening in the dark, and a balloon forcing a narrowed passage open.

A procedure to remove tissue from the cervical canal or the inner lining of the uterus.

A device used to stretch or enlarge an opening.

To make something thinner, weaker, less concentrated, or less pure by adding something to it.

DIM is a compound formed when the body breaks down indole-3-carbinol from cruciferous vegetables and is sold as a dietary supplement.

A substance being studied in the treatment of advanced melanoma (a type of skin cancer) and other types of cancer.

One drug with several jobs: the drowsiness that limits its daytime use for allergy is the same effect sold as a sleep aid.

A drug or substance used to treat hypercalcemia (abnormally high blood calcium) and bone pain caused by some types of cancer.

An exam of the inside of the back of the eye using an ophthalmoscope (a flashlight-sized instrument with a light source and a set of rotating lenses).

Discharge refers either to fluid released from the body or to a patient's formal release from a hospital or other care setting.

Cancer that continues to grow or spread.

The length of time after treatment for a specific disease during which a patient survives with no sign of the disease.

The percentage of people in a study or treatment group who have not died from a specific disease in a defined period of time.

A chemical meant for surfaces and equipment, strong enough to kill most germs but too harsh for living skin.

A joint that has come apart and stayed apart, which is a different problem from one that slipped and went back.

In medicine, a disturbance of normal functioning of the mind or body.

A mental state marked by confusion about time, place, or who one is.

Disseminate means to spread widely, describing how a disease process, infection, or information extends beyond its original, limited location.

In medicine, refers to a part of the body that is farther away from the center of the body than another part.

Removal of the body and tail of the pancreas.

Refers to cancer that has spread from the original (primary) tumor to distant organs or distant lymph nodes.

Refers to cancer that has spread from the original (primary) tumor to distant organs or distant lymph nodes.

Distraction most often names a technique that shifts attention away from pain, though the term also describes the surgical separation of bone or joint surfaces.

Two people in identical circumstances can report very different distress, which is why it is asked about directly rather than inferred.

It changes nothing about wanting a drink, only what happens afterward, and that consequence is the entire mechanism.

Diuretics increase urine output by altering how the kidneys handle salt and water, commonly used for high blood pressure and fluid retention.

Inflammation of one or more pouches or sacs that bulge out from the wall of a hollow organ, such as the colon.

Diverticulosis is the presence of multiple diverticula in the colon wall, usually causing no symptoms unless they become inflamed.

A diverticulum is a small pouch that bulges outward from the wall of a hollow organ such as the colon.

One word standing in for at least four different sensations, which is why the first question asked is what the feeling actually is.

Two meters of it are packed into a cell too small to see, arranged so any short stretch can still be found and read.

A process that allows thousands of pieces of DNA that are fixed to a glass slide to be analyzed at one time.

The enzyme that writes chemical tags onto DNA, and then copies that pattern into every new cell.

An enzyme (a protein that speeds up chemical reactions in the body) that attaches a methyl group to DNA.

DNA replication is the cellular process that copies a cell's entire DNA sequence before it divides into two daughter cells.

A type of advance directive in which a person states that healthcare providers should not perform cardiopulmonary resuscitation (restarting the heart) if his or her heart or breathing stops.

A type of advance directive in which a person states that healthcare providers should not perform cardiopulmonary resuscitation (restarting the heart) if his or her heart or breathing stops.

Dock refers to several related plants long used in traditional herbal preparations and, in some cases, eaten as a leafy food.

The active ingredient in a drug used to treat nausea and vomiting caused by cancer treatment.

A substance being studied in the treatment of cancer.

It preserves a messenger whose source the disease is steadily destroying, which is why the benefit is real but modest and temporary.

A staple of Chinese herbal formulas taken up in the West as a single remedy, which is not how it was traditionally given.

The person a transplanted organ, transfused blood or donated tissue comes from, whether living or recently deceased.

A type of therapy in which lymphocytes from the blood of a donor are given to a patient who has already received a stem cell transplant from the same donor.

A measured amount of a medicine or therapeutic agent given at one time or over an interval.

A chemotherapy treatment plan in which drugs are given with less time between treatments than in a standard chemotherapy treatment plan.

Refers to the effects of treatment with a drug.

Describes side effects of a drug or other treatment that are serious enough to prevent an increase in dose or level of that treatment.

The strength of a treatment given over a period of time.

A dosimetrist calculates and plans radiation dose distributions for cancer treatment, working alongside radiation oncologists and medical physicists to protect healthy tissue.

Radiation dose is measured and calculated through dosimetry, a process used in treatment planning as well as monitoring occupational and environmental exposure.

A trial design in which neither side knows who received what, so that expectation cannot quietly steer the result.

A procedure in which x-rays of the colon and rectum are taken after a liquid containing barium is put into the rectum.

Not how long one cell takes to divide, but how long a whole population takes to double, which is usually far longer.

Rinsing the vagina with liquid, a practice consistently linked with disruption of the bacteria that keep the organ balanced.

A disorder caused by the presence of an extra chromosome 21 and characterized by intellectual disability and distinguishing physical features.

One receptor sits in two very different places, which is how a single tablet ended up treating both blood pressure and prostate symptoms.

A drug used to treat high blood pressure and urinary problems caused by an enlarged prostate.

A substance being studied in the prevention of recurrent prostate cancer.

A drug that is used to treat many types of cancer and is being studied in the treatment of other types of cancer.

A drug that is used to treat many types of cancer and is being studied in the treatment of other types of cancer.

A form of the anticancer drug doxorubicin that is contained in very tiny, fat-like particles.

One of the few antibiotics that reaches organisms living inside human cells, which is why tick-borne and atypical infections come back to it.

The word durable is what matters here: this authority keeps working at the point when the person can no longer decide.

Belongs to a group of antihormone drugs.

A protein on the surface of certain cells that binds another protein called TRAIL, which may kill some cancer cells.

A protein on the surface of certain cells that binds another protein called TRAIL, which may kill some cancer cells.

In medicine, a drain is a tube or wick placed to remove fluid from a wound, surgical site, or body cavity as it accumulates.

Digital here means finger rather than electronic, and the reach of that finger is the main limitation of the whole examination.

One word doing two jobs, respectable and illicit, which is why regulators and clinicians often reach for medicine or medication instead.

The use of illegal drugs or the use of prescription or over-the-counter drugs for purposes other than those for which they are meant to be used, or in large amounts.

A log of study drugs kept by an investigator running a clinical trial.

A drug interaction alters a medication's effect when combined with another substance, potentially strengthening, weakening, or otherwise changing its action.

The failure of cancer cells, viruses, or bacteria to respond to a drug used to kill or weaken them.

The formal name for treating illness with medicines, whatever the route and whatever the outcome being sought.

A condition that occurs when the body gets used to a medicine so that either more medicine is needed or different medicine is needed.

Sexual climax without the release of semen from the penis.

Data and Safety Monitoring Board.