barbarous, brutal, cruel, fell, roughshod, savage, vicious -- ((of persons or their actions) able or disposed to inflict pain or suffering; "a barbarous crime"; "brutal beatings"; "cruel tortures"; "Stalin's roughshod treatment of the kulaks"; "a savage slap"; "vicious kicks")
condemnable, criminal, deplorable, reprehensible, vicious -- (bringing or deserving severe rebuke or censure; "a criminal waste of talent"; "a deplorable act of violence"; "adultery is as reprehensible for a husband as for a wife")
poisonous, venomous, vicious -- (marked by deep ill will; deliberately harmful; "poisonous hate"; "venomous criticism"; "vicious gossip")