To extend, send or spread out from a center like radii. / (transitive) To emit rays or waves. / (intransitive) To come out or proceed in rays or waves. / (transitive) To illuminate.

Radiating from a center; having rays or parts diverging from a center; radiated. / Surrounded by rays, such as the head of a saint in a religious picture.

(zoology) One of the Radiata.

Spontaneous emission of ionizing radiation as a consequence of a nuclear reaction, or directly from the breakdown of an unstable nucleus.

Exhibiting radioactivity. / (figuratively, rare) Dangerous and disgusting, particularly of people or ideas.

Any radioactive substance.

(physics) The electromagnetic radiation emitted from a body as a consequence of its temperature; increasing the temperature of the body increases the amount of radiation produced, and shifts it to shorter wavelengths (higher frequencies) in a manner explained only by quantum mechanics.

An image, often a photographic negative, produced by radiation other than normal light; especially an X-ray photograph. / An instrument for measuring and recording solar radiation.

To produce a radiograph image.

the process of making radiographs, and the science of analyzing them