anticlimax
/ænˈtɪkˌlɪmæks/Definitions
1. noun
a disappointing or less exciting event or conclusion after a period of tension or anticipation
“The anticlimax of the movie was the abrupt ending after an hour of suspenseful build-up.”
2. noun
a feeling of disappointment or letdown
“The excitement of the concert was followed by an anticlimax as the encore was just a repeat of the previous song.”
3. verb
to bring down or reduce something to a disappointing or less exciting state
“The plot twist anticlimaxed the entire story with a predictable outcome.”