1. Exposure to any form of radiation.

2. Treatment with a ray, such as ultraviolet rays, etc.

3. Apparent enlargement of objects, due to difference in illumination.

4. In food technology: exposure of food to controlled low levels of ionizing radiation to sterilize or disinfest it, without inducing radioactivity in the target. If in sealed containers, the product is sterile and can be stored under ambient conditions. Used for continuous flow disinfestation of grain at unloading facilities.