The Collaborative International Dictionary of English v.0.48:

Lowbred \Low"bred`\, a.
   Bred, or like one bred, in a low condition of life;
   characteristic or indicative of such breeding; rude;
   impolite; vulgar; as, a lowbred fellow; a lowbred remark.
   [1913 Webster]

WordNet (r) 3.0 (2006):

lowbred
    adj 1: (of persons) lacking in refinement or grace [syn: ill-
           bred, bounderish, lowbred, rude, underbred,
           yokelish]

The Devil's Dictionary (1881-1906):

LOW-BRED, adj.  "Raised" instead of brought up.