gaiety (n.)youdaoicibaDictYouDict[gaiety 词源字典]
"cheerfulness, mirth," 1630s, from French gaieté (Old French gaiete, 12c.), from gai "gay" (see gay). In the 1890s, in Britain, especially with reference to a London theater of that name, and the kind of musical shows and dancing girls it presented.[gaiety etymology, gaiety origin, 英语词源]