waterloo
n. countablen. a final and complete defeat. You use this when someone who was very successful finally loses everything in one big failure.
n. a decisive or final defeat or setback. Often used metaphorically to describe the end of a period of success or power.
The new law proved to be the minister's waterloo.
After years of winning every case, the lawyer met his waterloo when he faced a witness he couldn't rattle.
The ambitious expansion into the overseas market, once hailed as a visionary move, ultimately became the company's waterloo, leading to a total collapse of its share price.
From Middle Dutch, composed of water (“water”) + loo (“sacred wood, forest”). More at water, lea. cf. German Loh. Most places in English-speaking countries are named for the battle.
Usually used with a possessive (e.g., 'his waterloo') or the definite article ('the waterloo of').