underbred

adjective2

1. •
   Of inferior breeding or upbringing; vulgar, lacking in manners or finesse.

   • The art of governing these under-bred varlets lies more in the dignity of looks than in words […]. — 1748
2. •
   Not purebred; of an inferior strain.

   • I prefer both sire and dam to be well-bred, but a well-bred mare and an underbred horse will produce a faster animal than a thoroughbred horse and an underbred mare. — 1902