Radiation (noun)

1. The emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles that cause ionization.
2. Electromagnetic waves emitted by a source and spreading out in space, especially those produced by a nuclear explosion or by the radioactive decay of atomic nuclei.
3. The process by which energy is emitted as particles or waves.

Origin:

Late middle english (denoting rays from the sun): from latin radiatio(n-), from radiare 'to shine', from radius 'ray'.

Examples:

1. The doctor warned her that exposure to high levels of radiation could cause serious harm.
2. The satellite measures the radiation emitted by the sun.
3. The study found a link between prolonged exposure to radiation and an increased risk of cancer.
4. The gamma radiation from the radioactive material was a serious hazard to the workers.
5. The use of radiation therapy has become an important tool in the treatment of cancer.