trump card

American  

[truhmp kahrd, truhmp kahrd] / ˈtrʌmp ˌkɑrd, ˈtrʌmp ˈkɑrd /

noun

1. Cards. trump.

2. Informal. something that gives one person or group the advantage over another.

   The surprise witness was his trump card.

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trump card Cultural  

1. In general, something capable of making a decisive difference when used at the right moment; in certain card games, trump is the suit designated as having precedence over the others: “The prosecutor was about to win the case, when the defense lawyer produced her trump card: an eyewitness who testified that the accused was nowhere near the scene of the crime.”

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trump card Idioms  

1. A key resource to gain an advantage at the opportune moment, as in That surprise witness was the defense's trump card, or She played her trump card, announcing that the Senator would speak. This expression transfers the trump card of games such as bridge, which can win over a card of another suit, to other kinds of advantage. [Early 1800s]

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Etymology

Origin of trump card

First recorded in 1815–25

Example Sentences

For decades, Iran has held a single geopolitical trump card in its pocket — the ability to shut down oil-tanker traffic in the Strait of Hormuz.

From MarketWatch • Apr. 15, 2026

But if she has already decided to play the sport’s ultimate trump card, she isn’t tipping her hand.

From The Wall Street Journal • Feb. 11, 2026

Polanski himself wrote about his disappointment when he was not selected to run in Richmond Park, saying he was told "a local candidate is a trump card for many parties".

From BBC • Jan. 31, 2026

Brazil holds a trump card in tariff negotiations with the United States: its subsoil is rich in rare earth minerals coveted by manufacturers in a sector dominated by China.

From Barron's • Oct. 25, 2025

It is a sort of trump card in an intellectual game.

From "The Invention of Science" by David Wootton