flagitious
Guilty of terrible crimes; wicked, criminal.
literary
This young Nobleman was not only a flagitious Punster himself, but was accessary to the Punning of others, by Consent, by Provocation, by Connivance, and by Defence of the Evil committed […] .
Extremely brutal or wicked; heinous, monstrous.
literary
But if in Noble Minds ſome Dregs remain, / Not yet purg'd off, of Spleen and ſow'r Diſdain, / Diſcharge that Rage on more Provoking Crimes, / Nor fear a Dearth on theſe Flagitious Times.
Where it comes from
From Old French flagitieux or Latin flāgitiōsus, both ultimately from flāgitium (“shameful crime”), related to flagrum (“whip”).
Adapted from the Wiktionary entry flagitious (CC BY-SA 4.0).