hilarity
/hɪˈlærətɪ/noun
mass noun
1- extreme amusement, especially when expressed by laughter（尤指由笑声表达的）极度快乐：
his incredulous expression was the cause of much hilarity.
他那怀疑的神情引人大笑。
1.1
- boisterous merriment欢闹, 狂欢：
the noisy hilarity of the streets.
街上的狂欢。
词源
late Middle English （in the sense 'cheerfulness'）： from French hilarité, from Latin hilaritas 'cheerfulness, merriment', from hilaris （see HILARIOUS）.