Electromagnetic radiation emitted when a charged particle gives off energy as it moves through a transparent medium faster than the speed of light in that medium. The radiation is emitted in a cone whose half angle is greater for faster particles and media with higher refractive indices. Radiation occurs mainly in the visible and near UV (especially blue) region of the spectrum.
The name Cherenkov is sometimes also transliterated as Cerenkov.
References
Gladney, L. "Cerenkov Radiation." http://dept.physics.upenn.edu/balloon/cerenkov_radiation.html.
Smoot, G. "The Principle of the Radio Detection of Neutrinos." http://aether.lbl.gov/www/projects/neutrino/rand/radiodet.html.
