wild card
compound. B2 Upper Intermediate
compound. a person or thing that is unpredictable and can change the outcome of a situation. In card games, it is a card that can represent any other card.
compound. a person or thing whose influence or outcome is unpredictable; in card games, a card that can be designated as any other card to complete a set.
The new candidate is a wild card in this election.
The weather remains a wild card for the outdoor festival, as forecasts change every few hours.
While the incumbent holds a steady lead, the third-party challenger acts as a wild card, potentially siphoning enough votes to force a runoff.