wiðersaca m
From wiðer- (“against”) + saca. Cognate to Old High German widersahho, Old East Low Franconian withersacko, Old Saxon wiðarsako, Old Frisian witherseka, and German Widersacher. The Old High German word consists of wider- and -sahho, an agent noun belonging to Old High German sahhan (“to argue, fight, quarrel”), which is cognate to German Sache.