Radiation

n. energy radiated in the form of waves or particles; process of emitting energy in electromagnetic waves or moving particles; act of emitting, act of beaming or glowing

Radiation as used in physics, is energy in the form of waves or moving subatomic particles. Radiation can be classified as ionizing or non-ionizing radiation, depending on its effect on atomic matter. The most common use of the word "radiation" refers to ionizing radiation. Ionizing radiation has enough energy to ionize atoms or molecules while non-ionizing radiation does not. Radioactive material is a physical material that emits ionizing radiation.
See more at Wikipedia.org...

Radiation /ra·di·a·tion/ 1. divergence from a common center. 2. a structure made up of divergent elements, as one of the fiber tracts in the brain. [more]Radiation - Community and Resources

Noun
1. energy that is radiated or transmitted in the form of rays or waves or particles
(hypernym) energy
(hyponym) ionizing radiation
(derivation) radiate
2. the act of spreading outward from a central source
(hypernym) emission, emanation
(hyponym) bombardment
(derivation) radiate, ray
3. syndrome resulting from exposure to ionizing radiation (e.g., exposure to radioactive chemicals or to nuclear explosions); low doses cause diarrhea and nausea and vomiting and sometimes loss of hair; greater exposure can cause sterility and cataracts and some forms of cancer and other diseases; severe exposure can cause death within hours; "he was suffering from radiation"
(synonym) radiation sickness, radiation syndrome
(hypernym) syndrome
4. the spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay
(synonym) radioactivity
(hypernym) emission
(hyponym) corpuscular radiation, particulate radiation
5. the spread of a group of organisms into new habitats
(hypernym) natural process, natural action, action, activity
(hyponym) adaptive radiation
(derivation) diversify, radiate
6. a radial arrangement of nerve fibers connecting different parts of the brain
(hypernym) neural structure
(derivation) radiate, ray
7. (medicine) the treatment of disease (especially cancer) by exposure to radiation from a radioactive substance
(synonym) radiotherapy, radiation therapy, actinotherapy, irradiation
(hypernym) therapy
(hyponym) phototherapy
(classification) medicine, medical specialty

n. radiation, energy radiated in the form of waves or particles; process of emitting energy in electromagnetic waves or moving particles; act of emitting, act of beaming or glowing