expression, godan verb (-ru)
misfire; come to nothing; end in failure; fizzle out; fall flat
Used when a plan, attempt, or effort fails to produce the intended result, often with a sense of anticlimax. The literal meaning is 'to end as a misfire', from 不発 (misfire, failure to fire).
彼の計画は不発に終わった。
His plan ended in failure.
せっかくの提案も不発に終わってしまった。
Even the carefully prepared proposal fizzled out.