Englishrancorous
adjective
the campaign became increasingly rancorous as it progressed:
bitter, spiteful, hateful, resentful, acrimonious, malicious, malevolent, malign, malignant, hostile, antipathetic, venomous, poisonous, vindictive, evil-intentioned, ill-natured, baleful, vengeful, vitriolic, virulent, pernicious, mean, nasty;
informal bitchy, catty;
literary malefic, maleficent.
▷antonyms amicable.
rancorous Oxford Dictionary of English