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

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

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

The driving maul is still a trump card and the neat off-the-top variation that gave hooker Amy Cokayne her try will have opponents second-guessing themselves afresh.

From BBC • Aug. 22, 2025

Surging viewership for March Madness might be able to help Wiedenfels out there, but he’ll no longer have domestic NBA live games as his major trump card for other negotiations.

From Slate • Jun. 10, 2025

Yeah, it’s true, but I wish she’d stop picking fights so she can use her trump card.

From "The Hate U Give" by Angie Thomas