1) A medical or behavioral condition of which the onset is sudden. It manifests itself by symptoms of such severity that a prudent lay person with an average knowledge of medicine and health could reasonably expect that the absence of immediate medical attention would result in: placing the health of the afflicted person in serious jeopardy; placing the health of an individual with a behavioral health condition or others in serious jeopardy; causing serious impairment of the individual's bodily functions; causing serious dysfunction of any bodily organ or part; causing serious disfigurement of the afflicted individual.

2) Any instance for which, in the determination of the President, federal assistance is needed to supplement state and local efforts and capabilities to save lives and protect property and public health and safety or to lessen or avert the threat of a disaster in any part of the United States. Emergency Program: The interim program of the National Flood Insurance Program as implemented on an emergency basis to provide a first layer of subsidized insurance before the detailed risk studies from which actuarial rates are computed have been completed.

3) A. Any occasion or instance--such as a hurricane, tornado, storm, flood, tidal wave, tsunami, earthquake, volcanic eruption, landslide, mudslide, snowstorm, fire, explosion, nuclear accident, or any other natural or man-made catastrophe--that warrants action to save lives and to protect property, public health, and safety (FEMA definition). B. A sudden occurrence demanding immediate action that may be due to epidemics, technological catastrophes, strife or to natural or man-made causes (World Health Organization definition).

4) any sudden unforeseen crisis (usually involving danger) that requires immediate action