A complete or major failure; a fiasco or debacle where a plan or action goes badly wrong.
新製品の発売は予想外のトラブル続きで大失敗に終わった。
The new product launch ended in a complete failure due to unexpected problems.
彼のプレゼンは準備不足で大失敗だった。
His presentation was a big failure because he wasn't prepared.
料理は思ったより簡単だと思ったが、仕上がりは大失敗だ。
I thought the cooking would be easier, but the result was a disaster.
投資の判断を誤って大失敗を取り戻すのに何年もかかった。
He misjudged his investment and it took years to recover from the huge failure.