roc (n.)youdaoicibaDictYouDict[roc 词源字典]
large, ferocious bird of fable, 1570s, from Arabic rukhkh, from Persian rukh. Mentioned in Marco Polo's account of Madagascar, modern use is mostly from "Arabian Nights." Hence roc's egg "something marvelous or prodigious."[roc etymology, roc origin, 英语词源]