Disappointment or despair: feeling let down when expectations are not met; a sense of lost hope or discouragement.
合格発表を見て多くの受験生が失望した。
Many examinees were disappointed when they saw the results.
期待が大きかっただけに、失望も大きかった。
Because the expectations were high, the disappointment was also great.
彼の態度に失望した。
I was disappointed in his attitude.