reb (n.)

abbreviation of rebel (n.), 1862, a word from the U.S. Civil War, in which the Confederates embraced the North's designation of them as rebels. Along with rebelism (1862), rebeldom "the region or sphere of rebels" (1862) and others, for which see rebel (n.).

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Definitions of reb from WordNet

Reb (n.)
`Johnny' was applied as a nickname for Confederate soldiers by the Federal soldiers in the American Civil War; `greyback' derived from their grey Confederate uniforms;
Synonyms: Rebel / Johnny Reb / Johnny / greyback