Dictionary

Enter a word or phrase below to search our online dictionary of over 1,300 general medical terms, or click on a letter of the alphabet to view all terms beginning with that letter:

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Phrase Definition
halitosis Bad breath.
hallucination The sensory perception of sights, sounds or objects that don't really exist.
hammer The malleus, a hammer-shaped bone in the middle ear.
hamstring The tendon located in the back of the knee and lower thigh.
hand-foot-and-mouth disease A viral infection characterized by a blister-like rash of the hands, feet and mouth.
hangnail A loose piece of skin at one side of a fingernail.
Hansen's disease Leprosy.
harelip Cleft lip or palate.
Hashimoto's thyroiditis A degenerative autoimmune disease of the thyroid gland that ultimately results in a marked reduction in the amount of thyroid hormone produced.
hay fever Allergic sensitivity to certain mold spores and pollens. Allergic reaction includes sneezing, itchy eyes, sore throat and runny nose.
heart The hollow, muscular organ responsible for pumping blood through the circulatory system.
heart block A condition in which electrical impulses aren't properly transmitted from the heart's upper to the lower chambers.
heart failure Inability of the heart to adequately pump blood.
heartburn Indigestion. A burning sensation in the chest caused by a reflux of acid into the esophagus or too much acid in the stomach.
heat exhaustion Headache, profuse sweating, weakness, muscle cramps, nausea and vomiting caused by excessive exposure to heat.
heat stroke A serious failure of the body's heat-regulating mechanism resulting from excessive exposure to intense heat. Also called sunstroke.
hemangioma A tumor or swelling that's composed of blood vessels.
hematemesis The vomiting of blood.
hematology The branch of medicine that pertains to blood and the organs involved in forming blood.
hematoma A tumor-like mass of coagulated blood in the soft tissues. A contusion or bruise.
hematuria The presence of blood in the urine.
hemiplegia Paralysis (loss of feeling or movement) of one side of the body.
hemochromatosis A disorder of iron metabolism characterized by excessive amounts of iron in the skin, liver and other tissues.
hemoglobin The oxygen-carrying molecule in red blood cells.
hemolysis The destruction of red blood cells.
hemophilia An inherited disorder, nearly always in males, in which one of the normal blood-clotting factors is deficient.
hemoptysis A cough that produces blood.
hemorrhage Severe bleeding, usually from damage to a blood vessel.
hemorrhoid An enlarged vein inside or just outside the rectum.
hemostasis Control of bleeding.
hepatic Having to do with the liver.
hepatitis Inflammation or infection of the liver.
heredity Transmission of genetic traits from parents to children.
hermaphrodite A person with both male and female sex organs.
hernia An abnormal protrusion of part of an organ through an abnormal opening.
herpes A recurring viral skin infection characterized by clusters of small blisters. Typically, sores are located near the mouth (fever blisters or cold sores) or in the genital region (genital herpes).
heterosexual Having to do with the opposite sex.
hexachlorophene A detergent that kills germs.
hiccup A sudden, involuntary spasm of the diaphragm. The sound of hiccups is caused by the sudden intake of air.
hidradenitis Inflammation of the sweat glands.
hip The part of the body surrounding the joint between the femur and pelvic bones.
hirsutism Excessive hair growth, usually on the face and chest. Often caused by an imbalance in hormones.
histamine A substance released from certain cells in response to allergens, associated with the development of allergic symptoms, including itchy eyes, sneezing and congestion.
histoplasmosis A fungal disease caused by inhaling the spores of Histoplasma capsulatum.
HIV Human immunodeficiency virus. A virus that slowly destroys the immune system. The virus that causes AIDS.
hives A skin reaction characterized by swelling, itching and burning.
Hodgkin's disease A progressive form of lymphoma usually characterized by weakness, swollen lymph nodes, sweating, fever and weight loss.
homeopathy Medical treatment based on the theory that certain diseases can be cured by giving very small doses of substances that, in a healthy person, would produce symptoms like those of the disease.
homogenize To make more uniform in quality or consistency.
homosexual Having to do with the same sex.
hordeolum Inflammation of a gland on the eyelid. Also called a stye.
hormone A substance formed in an organ of the body and carried by body fluids to another organ or tissue, where it has a specific effect.
host An organism that harbors and provides sustenance for another organism.
housemaid's knee Swelling just below the kneecap, caused by the buildup of fluid in response to the constant pressure of kneeling.
humerus The bone in the upper arm.
humidifier A device for adding moisture to the air.
Huntington's chorea A hereditary form of chorea (sudden, jerky motions of the arms or other parts of the body) that usually affects people during their early 40s.
hydatid A cyst containing watery fluid and the larvae of certain tapeworms.
hydatid disease Infection with the larvae (cysts) of certain tapeworms.
hydatidiform mole A cystic tumor of the placental tissues of an abnormal pregnancy. Complications of this disorder include bleeding and infection.
hydrocele A painless swelling of the scrotum caused by the buildup of fluid in the outer covering of the testes.
hydrocephalus An enlargement of the head caused by the buildup of fluid within the ventricles of the brain. Also called "water on the brain."
hygiene The science of health and its maintenance.
hymen The membrane partly or completely closing the opening to the vagina.
hyperbaric Characterized by greater-than-normal pressure. Hyperbaric oxygen is a therapeutic treatment designed to increase blood oxygen by delivering oxygen in a chamber room with greater-than-normal pressure.
hyperemesis gravidarum Excessive morning sickness.
hyperglycemic High blood sugar.
hyperparathyroidism A condition caused by the overexcretion of parathyroid hormone resulting in changes in the bone and an elevated level of calcium in the blood.
hypertension Abnormally high blood pressure.
hyperthyroidism Overproduction of thyroid hormone.
hyperventilation Rapid or deep breathing producing faintness, numbness, chest pain, apprehension and tingling, and spasms of the extremities.
hypnosis A sleep-like state induced by the suggestions of a hypnotist.
hypnotic 1. Having to do with hypnosis. 2. Causing sleep.
hypochondriac Abnormal anxiety about one's health, often to the point of believing one is suffering from a serious disease.
hypodermic Beneath the skin.
hypoglycemia Low blood sugar.
hypoparathyroidism Parathyroid hormone insufficiency due to lack of secretion of the parathyroid gland.
hypopituitarism Deficient activity of the pituitary gland causing slowed growth in children, fatigue and decreased appetite in adults, and cessation of menstrual periods in women.
hyposensitization To treat with frequent, small injections of an antigen to decrease the symptoms of an allergy to that antigen. Also called desensitization.
hypospadias An abnormal opening of the urethra on the underside of the penis or into the vagina.
hypothalamus The portion of the brain responsible for temperature regulation and control of the pituitary gland.
hypothermia Low body temperature.
hypothyroidism A condition of low thyroid hormone production resulting in weight gain, hair loss, sluggishness and thickening of the skin.
hypoxia An abnormal condition resulting from decreased availability of oxygen in the body tissues.
hysterectomy Surgical removal of all or part of the uterus.
hysteria 1. Wild, uncontrolled excitement or other feelings. 2. A disorder in which anxiety is converted into physical symptoms that have no physical basis.