Late Middle English (in an earlier sense). From early Scandinavian (compare Old Icelandic hrogn, Norwegian rogn, Old Swedish rughn, romn (Swedish rom), Danish rogn (in early modern Danish as roughen, ruhen)), cognate with Middle Low German rōgen, Old High German rōgan (Middle High German rōgen, German Rogen), further etymology uncertain, perhaps ultimately from the same Indo-European base as Lithuanian kurkulas, Russian (regional) krek, krjak, Polish skrzek frogspawn, Slovene okrak waterweed. Compare roe and the Germanic forms cited at that entry.