adj. 25B6; adjective
a vicious killer : BRUTAL, ferocious, savage, violent, dangerous, ruthless, remorseless, merciless, heartless, callous, cruel, harsh, cold-blooded, inhuman, fierce, barbarous, barbaric, brutish, bloodthirsty, fiendish, sadistic, monstrous, murderous, homicidal.
a vicious hate campaign : MALICIOUS, malevolent, malignant, malign, spiteful, vindictive, venomous, poisonous, rancorous, mean, cruel, bitter, acrimonious, hostile, nasty; defamatory, slanderous; informal catty.
gentle, kindly.