IRRADIATION

irradiation. Irradiation, n. an illumination, a giving of light

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Ir‐ra′di‐a″tion (–ā″shŭn), n. [[Cf. F. irradiation.]] 1. 1. Act of irradiating, or state of being irradiated.
2. 2. Illumination; irradiance; brilliancy. Sir W. Scott.
3. 3. Fig.: Mental light or illumination. Sir M. Hale.
4. 4. (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.