happily (adv.)youdaoicibaDictYouDict[happily 词源字典]
mid-14c., "by chance or accident;" late 14c., "by good fortune, luckily," from happy + -ly (2). Sense of "in pleasant circumstances, with mental pleasure and contentment" is from 1510s. Happily ever after recorded by 1825.[happily etymology, happily origin, 英语词源]