*bherəg-, Proto-Indo-European root meaning "to shine; bright, white." It forms all or part of: Albert; Bertha; birch; bright; Egbert; Ethelbert; Gilbert; Herbert; Hubert; Lambert; Robert.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit bhrajate "shines, glitters;" Lithuanian brėkšti "to dawn;" Welsh berth "bright, beautiful."