I. ˈblakˌjak noun
( -s )
Etymology: black (I) + jack (jacket)
archaic Scotland : a black leather jerkin
II. noun
( -s )
1.
[ black (I) + jack (vessel)]
: a capacious vessel for beer or ale usually of tar-coated leather
2. or black jack
[ black (I) + jack (man); from its presence in lead ore, considered by the miners an impish intrusion of a worthless substance]
: sphalerite
3.
[ black (I) + jack (bird)]
: any of several dark-colored No. American ducks: as
a. : scaup duck
b. : black duck a
c. : ruddy duck
4.
[ black (I) + jack (instrument)]
: a small striking weapon typically consisting at the striking end of a leather-enclosed piece of lead or other heavy metal and at the handle end of a strap or springy shaft that increases the force of impact
5. or blackjack oak
[so called from the club-shaped leaves]
: a common often somewhat scrubby oak ( Quercus marilandica ) of the southeastern and southern United States that has a black bark, broad-ovate leaves, and a rather large ovoid-oblong acorn and that tends to form dense thickets — called also scrub oak
6.
[ black (I) + jack (knave of cards)]
a. : twenty-one
b. : a card game identical with twenty-one except that additional rules make it possible for any player to become the dealer
c. : an ace and a face card or ten received by a player as his first two cards in the game of blackjack (sense 6a or 6b) — called also natural
III. transitive verb
( -ed/-ing/-s )
1. : to strike with a blackjack
2. : to coerce by threats or pressure