Blackjack (formerly black jack and vingt-un) is a casino banking game. It is the most widely played casino banking game in the world. It uses decks of 52 cards and descends from a global family of casino banking games known as "twenty-one".

Synonyms of blackjack. 1. a. : a card game the object of which is to be dealt cards having a higher count than those of the dealer up to but not exceeding 21. called also twenty-one, vingt-et-un.