Disease

Definition

A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not due to any immediate external injury.

Related terms

Pathogen: An organism that causes disease in its host.

Epidemiology: The study and analysis of the distribution, patterns and determinants of health and disease conditions in defined populations.

Immune System: The body's defense against infectious organisms and other invaders through a series of steps called the immune response.