Words related to ruth
Old English hreowan (class II strong verb; past tense hreaw, past participle hrowen), "make (someone) sorry, cause (someone) to grieve, distress, affect with regret," transitive senses now obsolete, from Proto-Germanic *khrewan (which is source also of Old Frisian riowa, Middle Dutch rouwen, Old Dutch hrewan, German reuen "to sadden, cause repentance").
It is in part it has been blended with the Old English weak verb hreowian "feel pain or sorrow," and perhaps influenced by Old Norse hryggja "make sad." Both are from Proto-Germanic *khruwjan, all from PIE root *kreue- (2) "to push, strike" (see anacrusis).
The meaning "repent of, feel remorse for, feel regret for something or how it happened," is attested by c. 1200; the intransitive sense of "be sorrowful or penitent, experience grief" is recorded from 14c. Related: Rued; ruing.
King John. France, thou shalt rue this hour within this hour. ["King John," Act III, Scene 1]
"sorrow, repentance," Middle English reue, from Old English hreow "grief, repentance, sorrow, regret, penitence," from Proto-Germanic *hrewwo "pain; sadness, regret, repentance," source also of Frisian rou, Middle Dutch rou, Dutch rouw, Old High German (h)riuwa, German reue "sorrow, regret, repentance," nouns from the root of rue (v.).
Ruthful "pitiable, lamentable, causing ruth" (c. 1200) has fallen from use since late 17c. except as a deliberate archaism, perhaps in part because it had a conflicting sense of "compassionate, tender-hearted, full of ruth." Ruthness "compassion, pity" (early 14c.) died even younger. Related: Ruthlessly; ruthlessness.