Cards. a card having its value decided by the wishes of the players.
2.
a determining or important person or thing whose qualities are unknown, indeterminate, or unpredictable:
In a sailboat race the weather is the wild card.
3.
Tennis. a player, usually without ranking, who is allowed to enter a tournament at the discretion of the tournament committee after regularly qualifying competitors have been selected.
(sport) a player or team that has not qualified for a competition but is allowed to take part, at the organizers' discretion, after all the regular places have been taken
3.
an unpredictable element in a situation
4.
(computing) a symbol that can represent any character or group of characters, as in a filename
Word Origin and History for wild cards
wild card
n.
1927, in figurative sense, from literal use in poker, from wild (adj.) + card (n.). Sports team sense first recorded 1959.
Slang definitions & phrases for wild cards
wild card
modifier
: the wild-card slot/ last year's wildcard team
noun phrase
Something outside of the normal rules, category, etc; an unpredictable thing, event, etc: Being from Princeton wasn't like being from Jersey, it was a wild card(1920s+ Card games)
A team picked for a playoff by some more or less arbitrary method, not having won its championship during the season: We can always hope the Lions will be the wild card(1950s+ Sports)
[fr poker and other games, where in some cases one or more wild cards, having any value the player desires, may be designated]
Idioms and Phrases with wild cards
wild card
An unpredictable person or event, as in Don't count on his support—he's a wild card, or A traffic jam? That's a wild card we didn't expect. This expression comes from card games, especially poker, where it refers to a card that can stand for any rank chosen by the player who holds it. The term was adopted in sports for an additional player or team chosen to take part in a contest after the regular places have been taken. It is also used in computer terminology for a symbol that stands for one or more characters in searches for files that share a common specification. Its figurative use dates from the mid-1900s.