luc

From Latin lūx, lūcis (light) and the verb lūcēre (to shine, to give light). The root carries both the literal sense of light and the figurative sense of clarity. It shows up as luc-, lux-, and lucid-: lucid (clear in thought or expression), translucent (letting light through), pellucid (utterly clear), and lucubrate (to study by lamplight). The name Lucifer literally means 'light-bearer.'