blackguardly
1. [ adjective ] lacking principles or scruples
Synonyms: roguish scoundrelly rascally
Examples:

"the rascally rabble" "the tyranny of a scoundrelly aristocracy" - W.M. Thackaray "the captain was set adrift by his roguish crew"

Related terms: dishonest
Similar spelling:   blackguard
  black-haired
  Blackshear
  black_racer