The trump-card in your hand is a sight of my niece, and I'll take care you don't play it!
Of late she had been to him a valuable chattel—a trump-card, by which he could extract the good things of life out of another.
I saw too plainly that even though my wallet was gone I still held the trump-card—that he feared me.
Stillness, absolute immobility, was the trump-card to be always played in the wilderness when in doubt.
On the other hand, I had up my sleeve a trump-card—the death and cremation of the mysterious Gabrielle Engledue.
Fate had placed what seemed like a trump-card in the hands of the patiently-manoeuvring mother.
I saw that her curiosity was aroused and that she was eager to provide herself with a trump-card for the next meeting.
The clever, unscrupulous woman had reserved her trump-card to the last.
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.”