Che·ren·kov effect 
(chə-rĕngkôf, -kəf) also Če·ren·kov effect (chə-rĕngkôf, -kəf)
(chə-rĕngkôf, -kəf) also Če·ren·kov effect (chə-rĕngkôf, -kəf)n.
The emission of light by a charged particle passing through a transparent nonconducting liquid or solid material at a speed greater than the speed of light in that material.
[After Pavel Alekseevich Cherenkov (1904-1990), Russian physicist.]