Words related to rue
1775, in zoology, anatomy, etc., "a fold or wrinkle," plural of ruga (1775), from Latin ruga "a wrinkle in the face," from Proto-Italic *rouga-, which is of uncertain origin. "Since words for 'wrinkle' and 'crease' are often derived from 'to be rugged', from which also 'to belch' is often derived ..., the most obvious connection is with e-rugere 'to belch'" [de Vaan]. Related: Rugate; rugulose; rugose (1703); rugosity (1590s).
"unstressed syllable at the beginning of a verse," 1833, Latinized from Greek anakrousis "a pushing back," of a ship, "backing water," from anakrouein "to push back, stop short, check," from ana "back" (see ana-) + krouein "to strike," from PIE *kreue- (2) "to push, strike" (source also of Russian krusit, Lithuanian krušu, krušti "to smash, shatter," Old Church Slavonic kruchu "piece, bit of food," Old English hreowian "feel pain or sorrow," Old Norse hryggja "make sad"). Related: Anacrustic.
c. 1200, perhaps late Old English, ruthe, "misery, sorrow, grief;" also "pity, compassion, sorrow for the misery of another" (often in have ruth, take ruth); also "remorse, repentance, regret;" from Old Norse hryggð "ruth, sorrow," from hryggr "sorrowful, grieved" (see rue (v.)) + Proto-Germanic abstract noun suffix *-itho (see -th (2)).
Or else formed in English from reuwen "to rue" on the model of true/truth, etc. The Old English word was rue (n.2).