Axiom: universally accepted principle or rule; a proposition that is assumed without proof for the sake of studying the consequences that follow from it.
Epidemic: a widespread outbreak of an infectious disease; attacking or affecting many individuals in a community or a population.
Epidemiology: the branch of medicine dealing with the incidence and prevalence of disease in large populations and with detection of the source and cause of epidemics of infectious disease.
Pandemic: epidemic over a wide geographical area; occurring throughout a region or even throughout the world.
Paradigm: A set of assumptions, concepts, values, and practices that constitutes a way of viewing reality for the community that shares them, especially in an intellectual discipline.
Pathogen: An agent that causes disease, especially a living microorganism such as a bacterium or fungus.