noun the ensign of a pirate.
2. black-jack ·noun the quercus nigra, or barren oak.
3. black-jack ·noun a large leather vessel for beer, ·etc.
4. black-jack ·noun caramel or burnt sugar, used to color wines, spirits, ground coffee, ·etc.
5. black-jack ·noun a name given by english miners to sphalerite, or zinc blende;
called also false galena. ·see blende.