An Etymological Dictionary of the German Language/Annotated/rächen

rächen, verb, ‘to revenge, avenge,’ from Middle High German rëcken, Old High German rëhhan, older *wrëhhan, ‘to revenge, obtain satisfaction for some one’; corresponding to Gothic wrikan, ‘to persecute,’ gawrikan, ‘to avenge,’ Anglo-Saxon wrëcan, ‘to drive out, revenge, chastisise’ English to wreak, to which wreak is akin, Dutch wreken, ‘to revenge,’ and wraak, wrake, feminine, ‘revenge,’ Old Saxon wrekan, ‘to chastise.’ The Teutonic root wrek (compare also Rache, Recke, Wrak) with the primary meaning ‘to pursue, or rather expel, especially with the idea of punishment,’ is derived from a pre-Teutonic wreg, werg. It is usually compared with Latin urgeo, ‘I oppress,’ Sanscrit root vṛj, ‘to turn away,’ Greek εἴργω, ‘enemy,’ Lithuanian rárgas, ‘distress’ (vàrgti, ‘to be in want’), which imply an Aryan root werg, wreg.