jim crow /ˈʤɪmˈkro/
  Jim Crow n.
  1. A negro; -- said to be so called from a popular negro dance song, the refrain of which is “Wheel about and turn about and jump Jim Crow,” produced in 1835 by Thomas D. Rice (1808-1860), a famous negro minstrel; -- considered disparaging and offensive. [Offensive slang, U. S.]
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  Jim Crow
       n 1: barrier preventing blacks from participating in various
            activities with whites [syn: color bar, colour bar,
            color line, colour line]
       2: a crowbar fitted with a claw for pulling nails