Old English leah "open field, meadow, piece of untilled ground," earlier læch, recorded in place names, from Proto-Germanic *laukhaz (cognates: Old High German loh "cluster of bushes," and probably also Flemish -loo, which forms the second element in Waterloo), from PIE *louquo- (cognates: Sanskrit lokah "open space," Latin lucus "grove," Lithuanian laukas "open field"), perhaps from or related to *leuk- "to shine, be bright" (see light, n.).