실망해요 · 실망했어요 · 실망할 거예요 · 실망하지 마세요
to be disappointed
Example
시험 결과를 보고 많이 실망했어요.
I was really disappointed when I saw my test results.
Word parts
실 lose+망 hope
Literally 'to lose hope'.
Good to know
'Disappointed in someone' uses 한테 or 에게: 너한테 실망했어 = I'm disappointed in you.