"feel regret," Old English hreowan "make sorry, distress, grieve" (class II strong verb; past tense hreaw, past participle hrowen), from Proto-Germanic *khrewan (source also of Old Frisian riowa, Middle Dutch rouwen, Old Dutch hrewan, German reuen "to sadden, cause repentance"); in part, blended with Old English weak verb hreowian "feel pain or sorrow," and perhaps influenced by Old Norse hryggja "make sad," both from Proto-Germanic *khruwjan, all from PIE root *kreue- (2) "to push, strike" (see anacrusis). Related: Rued; ruing.