IPA: /ˌdɪsəˈpɔɪntɪd/
KK: /dɪsəˈpɔɪntɪd/
Feeling sad or unhappy because something did not happen as expected or because someone did not meet your hopes.
She was disappointed when her favorite team lost the game.
Disappointed is formed from "dis-" (meaning apart or away) and "appoint" (from Latin "ponere", meaning to place or put). The word describes the feeling of being let down or having one's hopes placed apart from reality.
Think of being 'let down' when something you hoped for is 'placed away' from you — 'dis-' means apart, and 'appoint' relates to placing expectations.