Irradiation

Part of speech: noun (n.)

1. Act of irradiating, or state of being irradiated.

2. Illumination; irradiance; brilliancy. Sir W. Scott.

3. Fig.: Mental light or illumination. Sir M. Hale.

4. 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.