1. (noun)blackjack oak, blackjack, jack oak, Quercus marilandica 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 Synonyms: northern pin oak, sap, blackflag, blackjack, vingt-et-un, pirateflag, twenty-one, cosh, blackjack oak, jack oak
4. (verb)blackjack, twenty-one, vingt-et-un 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 Synonyms: sap, blackflag, jack oak, blackjack, vingt-et-un, pirateflag, twenty-one, cosh, blackjack oak