Acrimonious
/ˌæk.rɪˈmoʊ.ni.əs/ adjective mediumMarked by sharp bitterness or ill will, especially in speech or disagreement.
The two business partners ended their acrimonious dispute only after a judge forced them to sell the company.
Memory Trick
'Acri-' echoes 'acrid,' a harsh, bitter smell — an acrimonious quarrel leaves the same bitter taste in everyone's mouth.