A playing card, of the trump suit that is held in reserve until needed to win a trick. / Something used to obtain an advantage, sometimes unscrupulously.

A person who uses card counting in pontoon or blackjack in order to obtain an advantage.

A strategy, in pontoon or blackjack, in which a player keeps a mental tally of the cards played in order to calculate the probability of certain cards being dealt and therefore obtain an advantage.

(US) A US work permit, officially known as United States Permanent Resident Card.

Enrolled as a member of an organization, and having a card to prove it; loyal to that organization or the cause it supports. / (by extension) Loyal and dedicated to some cause. / Official.

A confidence game in which the victim, or mark, is tricked into betting a sum of money that they can find the money card, for example the queen of hearts, among three face-down playing cards.

A fraudster who operates a game of three-card monte.

A computer hardware component designed to allow computers to communicate over a computer network.

(Australia) An informational card or leaflet published by a political party and distributed to the general public, usually near voting booths during election time, to indicate how to vote for a particular party.

(soccer) A red card, signifying a player's instant dismissal from the game for a single major foul or misconduct, distinct from and graver than a second yellow card, which a player may receive for several minor fouls.