mirth
n.
Old English myrgð "joy, pleasure," from Proto-Germanic *murgitha (cognates: Middle Dutch merchte), noun of quality from *murgjo- (see merry; also see -th(2)). Mirthquake "entertainment that excites convulsive laughter" first attested 1928, in reference to Harold Lloyd movies.
〔李〕[mir （=merry）欢乐的；-th ⇒“the condition of being merry欢乐的状态”→] n. merry fun or laughter；being joyous or gay欢笑；高兴