See quotations. Now obsolete.
1848. They say here [in Philadelphia] that they [servant galls] aint nothing but slewersbut I seed sum that I would tuck for respectable white galls if I had seed em in Georgia. Slewers or whatever they is, they is my own color, and a few dollars would make em as good as their mistresses, in the estimation of them that turns up ther noses at em now.W. T. Thompson, Major Joness Sketches of Travel, p. 107 (Phila.).
1848. [On the Hudson] you may call pore white men and wimmin waiters servants, slewers, or anything you please, but you must take monstrous good care how you speak to the free niggers.Id., p. 147.