wild card (also wildcard)

• 1. 

  N-COUNT If you refer to someone or something as a wild card in a particular situation, you mean that they cause uncertainty because you do not know how they will behave. 未知因素

  例：

  The wild card in the picture is eastern Europe.

  局势中的未知因素在东欧。

• 2. 

  N-COUNT A wildcard is a symbol such as * or ? used in some computing commands or searches in order to represent any character or range of characters. 通配符 (计算机指令中如*或?的符号，用于替代任一字符或系列字符) [计算机]

• 3. 

  N-COUNT In card games, if a particular card is named as a wild card, the player who holds it may give it any value he chooses. 百搭牌 (牌戏中由持牌人决定牌值的牌)

  例：

  Look. I have a straight of 3, 4, 6, 7 and the wild card for the 5.

  看，我有连着的3，4，6，7， 还有一张百搭牌作5。