irradiation

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The act of exposing or the condition of being exposed to radiation.
2. n. The use or application of ionizing radiation, especially in medical treatment and for the sterilization or preservation of food.

Century Dictionary and Cyclopedia

1. n. The act of irradiating or emitting beams of light; illumination; brightness emitted; enlightenment.
2. n. In physics, the phenomenon of the apparent enlargement of an object strongly illuminated, when seen against a dark ground. It was explained by Plateau as due to the extension of the impression upon the nerves of the retina beyond the outlines of the image; Helmholtz, however, has ascribed it to the want of perfect accommodation in the eye, leading to the formation of diffusion images about the proper image of a bright object, so that it encroaches upon the dark space about it, and hence appears larger than it really is. Irradiation increases with the brightness of the object, diminishes as the illumination of the object and that of the field of view approach equality, and vanishes when they become equal.
3. n. In neurology, the diffusion of a nervous impulse to parts outside the normal path of conduction.
4. n. In therapeutics, subjection to the influence of X-rays or other form of radioactivity.
5. n. In anatomy, the disposition of fibrous or other structures in stellate form.
6. n. In chem., exposure to radiant light: as, some substances are said to phosphoresce by irradiation.

Wiktionary

1. n. An act of irradiating, or state of being irradiated.
2. n. obsolete illumination; irradiance; brilliance.
3. n. obsolete figurative: mental light or illumination.
4. n. obsolete the apparent enlargement of a bright object seen upon a dark ground, due to the fact that the portions of the retina around the image are stimulated by the intense light; as when a dark spot on a white ground appears smaller, or a white spot on a dark ground larger, than it really is, especially when a little out of focus.
5. n. uncountable a process of sterilisation whereby radiation is passed through a bag containing food, utensils, etc., to sterilise the contents.

GNU Webster's 1913

1. n. Act of irradiating, or state of being irradiated.
2. n. Illumination; irradiance; brilliancy.
3. n. Fig.: Mental light or illumination.
4. n. (Opt.) The apparent enlargement of a bright object seen upon a dark ground, due to the fact that the portions of the retina around the image are stimulated by the intense light; as when a dark spot on a white ground appears smaller, or a white spot on a dark ground larger, than it really is, esp. when a little out of focus.

WordNet 3.0

1. n. (physiology) the spread of sensory neural impulses in the cortex
2. n. (medicine) the treatment of disease (especially cancer) by exposure to a radioactive substance
3. n. a column of light (as from a beacon)
4. n. the condition of being exposed to radiation
5. n. the apparent enlargement of a bright object when viewed against a dark background
6. n. (Pavolvian conditioning) the elicitation of a conditioned response by stimulation similar but not identical to the original stimulus