wild card

noun
1
a card that has no value of its own and takes the value of any card that the player chooses
کارت آزاد, کارت وحشی, برگه جایگزین
2
an opportunity for somebody to play in a competition when they have not qualified in the usual way; a player who enters a competition in this way
ورود استثنائی, دعوت ویژه, بازیکن انتخابی
He was given a wild card for the tournament.
She was beaten in the semi-finals by wild card Louise Smith.
3
a symbol that can represent any letter or number
نماد جایگزین, نماد تطبیقی
An asterisk is commonly used as a wild card.
a wild-card search
4
a person or thing whose behaviour or effect is difficult to predict
عنصر غیرقابل پیش‌بینی, عامل غیرقابل پیش‌بینی, شخص غیرقابل پیش‌بینی
The Nationalist party is the wild card in the election.