An Etymological Dictionary of the German Language/rügen
rügen, vb., ‘to denounce, censure, reprove,’ from MidHG. rüegen, OHG. ruogen, ‘to accuse, charge with, blame,’ for an earlier wrogjan; comp. Goth. wrôhjan, OSax. wrôgjan, AS. wrêgan, ‘to accuse, charge with.’ Allied to ModHG. Rüge, ‘censure, blame, crime,’ MidHG. rüege, Goth. wrôhs, ‘accusation,’ OSax. wrôht, ‘strife,’ AS. wrôht, ‘accusation, strife, crime.’ The Goth. forms with h compared with the g in the other terms point to Aryan k, which was the cause of the grammatical change of h to g. An Aryan root wrôk, wrâk, has not yet been discovered.