Definition for Radiation sickness
From Biology Forums Dictionary
Radiation sickness results when humans (or other animals) are exposed to very large doses of ionizing radiation.
Radiation exposure can occur as a single large exposure (acute), or a series of small exposures spread over time (chronic). Exposure may be accidental or intentional (as in radiation therapy).
Radiation sickness is generally associated with acute exposure and has a characteristic set of symptoms that appear in an orderly fashion. Chronic exposure is usually associated with delayed medical problems such as cancer and premature aging, which may happen over a long period of time.