A wicked or dishonest person; a villain or rogue.
From Italian 'scoundro' or Spanish 'escondidas' (rascal, possibly meaning 'hidden one'), the word entered English in the 16th century with French influences.
Scoundrel has an almost playful quality despite meaning something genuinely bad—it's the insult of choice for comic book villains and adventure novels, which is why it feels more theatrical than truly threatening.
Complete word intelligence in one call. Free tier — 50 lookups/day.