/ray"dee ay'teuhr/ , n.
1. a person or thing that radiates.
2. any of various heating devices, as a series or coil of pipes through which steam or hot water passes.
3. a device constructed from thin-walled tubes and metal fins, used for cooling circulating water, as in an automobile engine.
4. Radio. a transmitting antenna.
[ 1830-40; RADIATE + -OR 2 ]