irradiation

n. [ Cf. F. irradiation. ] [ 1913 Webster ]

1. Act of irradiating, or state of being irradiated; as, irradiation of foods with X-rays can preserve their freshness by killing the bacteria that cause spoilage . [ 1913 Webster +PJC ]

2. Illumination; irradiance; brilliancy. Sir W. Scott. [ 1913 Webster ]

3. Fig.: Mental light or illumination. Sir M. Hale. [ 1913 Webster ]

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. [ 1913 Webster ]