Dictionary of Medical Terms

Gain a better understanding of medical terminology by searching our dictionary of more than 1,300 terms.

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All terms that start with the letter H

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histamine

A substance released from certain cells in response to allergens, associated with the development of allergic symptoms, including itchy eyes,…
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,…
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…
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…
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…
hygiene

The science of health and its maintenance.