joviality       
noun [ U ]  formal uk/ˌdʒəʊ.viˈæl.ə.ti/ us/ˌdʒoʊ.viˈæl.ə.t̬i/
 (人)友善,快乐;(情况)欢乐,愉悦
the quality in a person of being friendly and in a good mood, or of a situation being enjoyable, friendly and pleasant
  There was an air of joviality in the room. 房间里弥漫着欢快的气氛。 
 She had a forced joviality that made us suspicious. 她强装笑颜,这让我们产生了怀疑。 
 See: jovial
 - More examples
 - He greeted them all with boundless joviality.
 - I noticed her increased joviality.
 - "All right, all right, enough of the joviality," said Gregson.
 - His joviality was dropped and replaced with irritability.