RhymeZone: black-jack definitions

Definitions of black-jack:

noun: (obsolete, mineralogy, UK) Sphalerite; zincblende.
noun: (obsolete) Caramel or burnt sugar, used to colour wines, spirits, ground coffee, etc.
noun: (obsolete) A large leather vessel for beer, etc.
noun: (obsolete) The Quercus nigra, water oak or barren oak.
noun: (obsolete, circa 1700s) A native African longshoreman or sailor working on a boat.

(Definitions from Wiktionary)