blackjack Meaning, Definition & Usage

1. noun a common scrubby deciduous tree of central and southeastern United States having dark bark and broad three-lobed (club-shaped) leaves; tends to form dense thickets
   jack oak; Quercus marilandica; blackjack oak.
   
2. noun a piece of metal covered by leather with a flexible handle; used for hitting people
   sap; cosh.
   
3. noun a flag usually bearing a white skull and crossbones on a black background; indicates a pirate ship
   black flag; Jolly Roger; pirate flag.
   
4. noun a gambling game using cards; the object is to hold cards having a higher count than those dealt to the banker up to but not exceeding 21
   vingt-et-un; twenty-one.
   
5. verb exert pressure on someone through threats
   pressure; blackmail.
   

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