dis|ap|point|ment [ ,dısə`pɔıntmənt ] noun **
1. ) uncount the feeling of being unhappy because something you hoped for or expected did not happen or because someone or something was not as good as you expected:
disappointment at: Diplomats expressed disappointment at the lack of progress.
to someone's disappointment (=making someone disappointed): Jackson canceled the concert, to the great disappointment of his fans.
disappointment with: The representatives acknowledged their disappointment with the negotiations.
2. ) count someone or something that is not as good as you thought they would be:
a big/great/bitter/major disappointment: Newcombe has described the defeat as the biggest disappointment of his career.
be a disappointment to someone: I'm such a disappointment to her.

Usage of the words and phrases in modern English. 2013.