Black-jack

Black"-jack`, n. 1. (Min.) A name given by English miners to sphalerite, or zinc blende; -- called also false galena. See Blende.

2. Caramel or burnt sugar, used to color wines, spirits, ground coffee, etc.

3. A large leather vessel for beer, etc. [Obs.]

4. (Bot.) The Quercus nigra, or barren oak.

5. The ensign of a pirate.