Discouragement or despondency: feeling disappointed and losing hope or spirit when expectations are not met.
試験に落ちて彼は大いに落胆した。
He was greatly disappointed after failing the exam.
期待していた結果と違って落胆した様子だった。
He looked disappointed because the results differed from what he expected.
落胆しないで、次の機会に備えよう。
Don't be discouraged; prepare for the next opportunity.