feeling sad or displeased because something has not happened as hoped

निराश

English Usage: She felt disappointed when her team lost the game.

Hindi Usage: जब उसकी टीम खेल हार गई, तो वह निराश महसूस कर रही थी.

to fail to fulfill the hopes or expectations of someone

निराश करना

English Usage: I didn’t mean to disappoint you with my decision.

Hindi Usage: मैं अपने फैसले से आपको निराश करना नहीं चाहता था.