"scoundrelly" in the adjective sense
1. rascally, roguish, scoundrelly, blackguardly
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"
Source: WordNet® (An amazing lexical database of English)
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