Ir*ra`di*a"tion (?), n. [Cf. F. irradiation.]


Act of irradiating, or state of being irradiated.


Illumination; irradiance; brilliancy.

Sir W. Scott.


Fig.: Mental light or illumination.

Sir M. Hale.

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.


© Webster 1913.