a feeling of unhappiness because something is not as good as you expected, or has not happened in the way you hoped:
He could see the disappointment in her eyes.
to somebody's (great) disappointment
To Edward's disappointment, Gina never turned up at the party.
disappointment at/with/over etc
the managers' disappointment with the results
Several people expressed disappointment at the delay.
her disappointment that she hadn't been picked
She hid her bitter disappointment.
someone or something that is not as good as you hoped or expected:
The movie was kind of a disappointment.
The loss was a bitter disappointment.
She felt she was a disappointment to her family.
The team's performance has been a disappointment for the fans.