non-event

Word family  noun event non-event eventuality uneventfulness adjective eventful ≠ uneventful eventual adverb eventfully ≠ uneventfully eventually

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++ˌnon-eˈvent noun [countable usually singular]  DISAPPOINTEDan event that is disappointing because it is much less interesting, exciting, or important than you expected 远不如预料中那么有趣[兴奋，重要]的事；令人大失所望的事 In the end, the match turned out to be a non-event. 那场比赛最终令人大失所望。

Examples from the Corpus

non-event• Carver's testimony turned out to be a non-event.

ˌnon-eˈvent nounChineseSyllable  

event is because Corpus an it is less that much disappointing

non-event
ˌnon-eˈvent noun [countable usually singular]an event that is disappointing because it is much less interesting, exciting, or important than you expected:
    In the end, the match turned out to be a non-event.

non-eventBrE /ˌnɒn ɪˈvent/ 🔊NAmE /ˌnɑːn ɪˈvent/ 🔊 noun (informal) an event that was expected to be interesting, exciting and popular but is in fact very disappointing 令人失望的事；扫兴的事 SYN anticlimax