1. 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.
Pronunciation: (wīld'kärd"), [key]
1. of, constituting, or including a wild card.
2. Informal.of, being, or including an unpredictable or unproven element, person, item, etc.
3. Sports.of, being, or including an unseeded or unproven participant or team, as a team in a championship tournament that has not placed first in its league or area.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.