Medical terms A–Z

Naming an outcome and not a method, the word covers anything that leaves cancer cells broken open, from a drug to a virus.

Treatment using an oncolytic virus (a virus that infects and breaks down cancer cells but not normal cells ).

Turning an infection into a treatment, where the burst tumor cell matters less than the alarm its debris raises.

Bursting the tumor cell is only half the mechanism; the wreckage left behind shows the immune system what it should be hunting.

A drug used to treat acute leukemia.

How soon a drug starts working, which is a separate question from how strongly it works or how long it lasts.

Oophorectomy is the surgical removal of one or both ovaries, performed for conditions such as ovarian masses, cancer risk, or disease.

An operation to remove all or part of the colon through a long incision made in the wall of the abdomen.

A type of study in which both the health providers and the patients are aware of the drug or treatment being given.

An operation to remove part or all of the prostate gland through an incision in the lower abdomen or perineum (the area between the anus and scrotum).

Surgery to remove part or all of an organ or a tumor and nearby lymph nodes.

Describes a condition that can be treated by surgery.

Ophthalmic describes anything relating to the eye, including its anatomy, diseases, examinations, and medications formulated for eye use.

A doctor who specializes in diagnosing and treating eye problems, including injury and disease.

A handheld light and lens that turns the pupil into a window onto living blood vessels and nerve tissue.

An opiate is a pain-relieving substance derived directly from opium, a narrower category than the broader term opioid, which also includes synthetic drugs.

These drugs do not remove the source of pain; they change how the nervous system registers it, and the other effects follow from that.

An infection caused by an organism that does not normally cause disease.

A drug used to increase the number of blood cells, especially platelets, in some cancer patients receiving chemotherapy.

A substance being studied in the treatment of diarrhea caused by infection with Clostridium difficile (a type of bacteria that can grow without oxygen) in cancer patients.

The place in the brain where some of the optic nerve fibers coming from one eye cross optic nerve fibers from the other eye.

The place in the brain where some of the optic nerve fibers coming from one eye cross optic nerve fibers from the other eye.

The optic nerve carries visual signals from the retina to the brain and is itself considered an extension of brain tissue.

A rare, slow-growing tumor that usually forms in the optic nerve, optic chiasm, or optic tract.

The nerves that travel from the optic chiasm (place in the brain where some of the optic nerve fibers cross) into certain parts of the brain involved in vision.

In medicine, a technique that uses low power light, fiberoptic instruments, and detectors to examine tissue.

Distinct from denial: an accurate grasp of a diagnosis and a hopeful outlook about living with it can sit together.

Oral describes anything relating to the mouth, including its anatomy, medications taken by swallowing, and examinations of the mouth and throat.

A dentist who specializes in surgery of the mouth, face, and jaw.

Oral cancer arises in the tissues of the mouth, most often as squamous cell carcinoma linked to tobacco and heavy alcohol use.

A precisely bounded space rather than a loose word for mouth, which is why the border with the throat matters so much.

Cancer that forms in tissues of the oral cavity (the mouth).

A daily hormone tablet that prevents pregnancy chiefly by keeping the ovary from releasing an egg at all.

A dentist with special training in surgery of the mouth and jaw.

Surgery to remove one or both testicles.

Surgery to remove one or both testicles.

The level of organization between tissue and body system, where several kinds of tissue combine to do one job.

Organic food is grown and processed under defined regulatory standards that restrict synthetic fertilizers, pesticides, and similar inputs used in conventional agriculture.

A biology word that shrinks in the clinic, where the organism almost always means whatever has grown in the culture bottle.

The final part of the sex act, which involves contraction of sexual organs and a sudden release of endorphins, leading to a feeling of pleasure.

Oropharyngeal cancer develops in the back of the throat, including the tonsils and base of tongue, with a growing share linked to HPV infection.

The oropharynx is the middle section of the throat, positioned behind the mouth and connecting the oral cavity to the lower throat and esophagus.

A system in which medical doctors and other healthcare professionals (such as nurses, pharmacists, and therapists) treat symptoms and diseases using drugs, radiation, or surgery.

In medicine, refers to something that occurs in the normal or usual place in the body.

A drug used to treat certain types of non-small cell lung cancer.

A substance being studied in the treatment of cancer.

The concentration of particles dissolved in a fluid.

Water follows salt and sugar rather than the other way around, and most of the body's fluid shifts follow from that one rule.

A chronic condition in which both the breakdown and regrowth of bone are increased.

Calling it wear and tear undersells it, since cartilage cells actively dismantle their own matrix and the bone changes alongside.

A cancer of the bone that usually affects the large bones of the arm or leg.

An osteolytic process breaks down bone tissue faster than the body can rebuild it, often appearing as a darkened area on imaging.

Osteomyelitis is a bone infection that can arise from bloodstream spread, direct injury, or a nearby infected wound such as a diabetic foot ulcer.

A condition in which there is a lower-than-normal bone mass or bone mineral density (the amount of bone mineral contained in a certain amount of bone).

Spinal fractures are the most common kind and often pass unnoticed, surfacing later as lost height and a stooped upper back.

The tumor makes bone, which is what gives it away on an X-ray and what separates it from cancer that merely arrived in bone.

An operation to create an opening (a stoma) from an area inside the body to the outside.

OTC identifies a medicine or health product available without a prescription, based on an established safety profile suitable for self-selection and use.

Children are affected far more than adults because the tube ventilating the middle ear is shorter and lies more level.

The specialty is defined by a region of the body rather than by one organ, one disease process or one kind of treatment.

A measure of weight (one-sixteenth pound) and volume (one-eighth cup).

Choosing which result to measure decides what a study is able to claim, which is why the choice is fixed before anyone is enrolled.

A person can spend a night in a hospital bed and still count as an outpatient, because the label tracks admission status rather than hours.

The ovaries sit deep in the pelvis with no surface to feel, so ovarian problems tend to announce themselves indirectly.

Surgery, radiation therapy, or a drug treatment to stop the functioning of the ovaries.

A condition in which cells that may become cancer form in the thin layer of tissue that covers an ovary (female reproductive gland in which eggs are made).

Early symptoms are so ordinary, bloating and pelvic discomfort among them, that the disease is usually advanced when found.

A cancer vaccine comprised of synthetic peptides corresponding to naturally-occurring peptides derived from ovarian cancer cell antigens.

Cancer that occurs in the cells on the surface of the ovary.

An abnormal mass of tissue that forms in germ (egg) cells in the ovary (female reproductive gland in which the eggs are formed).

Surgery, radiation therapy, or a drug treatment to stop the functioning of the ovaries.

One of a pair of female reproductive glands in which the ova, or eggs, are formed.

(Other name for: autologous dinitrophenyl-modified ovarian cancer vaccine)

Medicines a person can buy and choose without a clinician, judged safe enough for self-treatment of problems people can recognize.

Too much thyroid hormone.

The percentage of people in a study or treatment group who are alive for a certain period of time after they were diagnosed with or treated for a disease, such as cancer.

The threshold is not a fixed quantity: body size, kidney and liver function, and whatever else is already on board all move it.

In biology, to make too many copies of a protein or other substance.

A group of genetic disorders in which there is an abnormal increase in the size of the body or a body part that is often noted at birth.

(Other name for: norgestrel)

The second half of the cycle runs to a fairly fixed length, so it is the first half that decides when release happens.

A protein being studied in the treatment of cancer.

This chemotherapy drug is notable for a distinctive nerve related side effect that can be triggered or worsened by exposure to cold.

(Other name for: oxandrolone)

A laboratory-made relative of testosterone shaped to build muscle with less of the male hormone effect.

A substance that blocks the process cells use to repair DNA.

Oxidation is a chemical reaction in which atoms or molecules lose electrons, a process linked in the body to both essential metabolism and cellular damage.

A chemical process in which oxygen is used to make energy from carbohydrates (sugars).

Not simply a shortage of antioxidants but a balance tipped the wrong way, with damage as the result rather than the cause.

An oxide is any compound formed when oxygen chemically combines with another element, a category spanning substances as different as water, rust, and certain plant oils.

To oxidize is to react chemically with oxygen or a similar substance, a process linked in the body to both energy production and cell damage.

(Other name for: 5-hydroxytryptophan)

(Other name for: methoxsalen)

(Other name for: methoxsalen)

Oxycodone hydrochloride is the salt form of oxycodone, an opioid pain reliever prescribed for moderate to severe pain.

The whole design rests on the tablet staying intact, since crushing it converts a slow dose into a large immediate one.

Carrying it is one job and delivering it is another, which is why a normal saturation reading can sit above starving tissue.

A test that measures the amount of oxygen being carried by red blood cells.

Supplemental oxygen given as a treatment for low blood oxygen, delivered at a controlled concentration rather than as much as possible.

A radioactive form of the element phosphorus used in the treatment of cancer.