Health Glossary

Demystifying medical language. Browse or search for clear, human-centered explanations of common medical terms.

Hazard

The inherent potential of a substance, organism, activity, or situation to cause harm. Hazard describes what can cause harm, rather…
View Definition →

Heatstroke

Heatstroke is a life-threatening medical emergency in which the body becomes dangerously overheated and its ability to regulate temperature fails,…
View Definition →

Hepatitis

Inflammation of the liver. Hepatitis can have many causes, including viral infections, alcohol, certain medicines or toxins, autoimmune disease, and…
View Definition →

Herd Immunity

Indirect protection from an infectious disease that occurs when a sufficiently large proportion of a population is immune, making transmission…
View Definition →

HIV

Human immunodeficiency virus (HIV) is a retrovirus that attacks cells of the immune system and, without effective treatment, can progressively…
View Definition →

Homeostasis

Homeostasis is the process by which the body maintains relatively stable internal conditions despite changes inside or outside the body.…
View Definition →

Hormone

A chemical messenger produced by cells or tissues that travels through body fluids or acts locally to regulate the activity…
View Definition →

Hygiene

Practices and conditions that help maintain health and reduce exposure to infectious agents and other harmful substances. Hygiene includes practices…
View Definition →

Hypertension

A chronic medical condition in which blood pressure remains persistently elevated above the level considered appropriate for health. Hypertension develops…
View Definition →