Wiktionary

1. c-decay(Noun)

   A discredited theory proposed by creationists in order to support the belief that the universe is a few thousand years old that claims that the speed of light has decreased over time, meaning that objects millions of light years away are visible today (whereas a constant speed of light would imply that the universe is millions of years old and so contradict this belief).

Origin: c, the symbol used in physics for the speed of light, decay