radiation

ra·di·a·tion

noun \ˌrād-ē-ˈā-shən\

Definition of RADIATION

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>