blackguardly

from WordNet (r) 3.0 (2006)

blackguardly
    adj 1: lacking principles or scruples; "the rascally rabble";
           "the tyranny of a scoundrelly aristocracy" - W.M.
           Thackaray; "the captain was set adrift by his roguish
           crew" [syn: {rascally}, {roguish}, {scoundrelly},
           {blackguardly}]

from The Collaborative International Dictionary of English v.0.48

Blackguardly \Black"guard*ly\, adv. & a.
   In the manner of or resembling a blackguard; abusive;
   scurrilous; ruffianly.
   [1913 Webster]