aloudyoudaoicibaDictYouDict[aloud 词源字典]
aloud: [14] Aloud was formed in Middle English from the adjective loud and the prefix a-, as in abroad; it does not appear to have had a direct Old English antecedent *on loud. Its opposite, alow ‘quietly’, did not survive the 15th century.
=> loud[aloud etymology, aloud origin, 英语词源]
aloud (adv.)youdaoicibaDictYouDict
late 14c., from a- (1) + loud.