moon goddess, equivalent of Latin Luna, from Greek selene "the moon; name of the moon goddess," related to selas "light, brightness, bright flame, flash of an eye," from PIE root *swel- (2) "to shine, beam" (cognates: Sanskrit svargah "heaven," Lithuanian svilti "to singe," Old English swelan "to be burnt up," Middle Low German swelan "to smolder"); related to swelter, sultry. Related: Selenian "of or pertaining to the moon as a world," 1660s.