aqua (n.)youdaoicibaDictYouDict[aqua 词源字典]
"water," late 14c.; see aqua-. Used in late Middle English in combinations to mean "decoction, solution" (as in aqua regia, a mix of concentrated acids, literally "royal water," so called for its power to dissolve gold and other "noble" metals). As the name of a light greenish-blue color, 1936.[aqua etymology, aqua origin, 英语词源]