1. The subjective enlargement of a bright object seen against a dark background.
2. Exposure to the action of electromagnetic radiation (heat, light, x-rays).
3. The spreading of nervous impulses from one area in the brain or cord, or from a tract, to another tract.
The information shown above for irradiation is provided by Stedman's.
* Stedman's, part of Lippincott Williams & Wilkins, provide a comprehensive line of health-science publications for healthcare professionals and medical students.