Main Entry: ra·di·a·tion

Pronunciation: \ˌrād-ē-ˈā-shən\

Function: noun

1 : energy radiated in the form of waves or particles
2 a : the action or process of radiating <with radiation of the pain there may be tenderness over the sciatic nerve—J. A. Key> b (1) : the process of emitting radiant energy in the form of waves or particles (2) : the combined processes of emission, transmission, and absorption of radiant energy
3 : a tract of nerve fibers within the brain ; especially : one concerned with the distribution of impulses arising from sensory stimuli to the relevant coordinating centers and nuclei <the optic radiations>