名詞 black jack:

1. 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
   同義詞：blackjack oak, blackjack, jack oak, Quercus marilandica
2. a piece of metal covered by leather with a flexible handle; used for hitting people
   同義詞：blackjack, cosh, sap
3. a flag usually bearing a white skull and crossbones on a black background; indicates a pirate ship
   同義詞：black flag, pirate flag, Jolly Roger, blackjack
4. a gambling game using cards; the object is to hold cards having a higher count than those dealt to the bank up to but not exceeding 21
   同義詞：blackjack, twenty-one, vingt-et-un

動詞 black jack:

1. exert pressure on someone through threats
   同義詞：blackmail, blackjack, pressure