·noun Fig.: Mental light or illumination.
II. Irradiation ·noun Illumination; irradiance; brilliancy.
III. Irradiation ·noun Act of irradiating, or state of being irradiated.
IV. Irradiation ·noun 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.