hilarity

 
Pronunciation: /hɪˈlarɪti/

noun

[mass noun]
  • extreme amusement, especially when expressed by laughter: his incredulous expression was the cause of much hilarity
  • archaic boisterous merriment: by midnight the hilarity had increased

Origin:

late Middle English (in the sense 'cheerfulness'): from French hilarité, from Latin hilaritas 'cheerfulness, merriment', from hilaris (see hilarious)