Synonyms for Vindictive (same or very similar meaning)
WordNet sense 1 (disposed to seek revenge or intended for revenge):
revengeful, vengeful
WordNet sense 2 (unwilling or unable to forgive or show mercy):
unforgiving
WordNet sense 3 (showing malicious ill will and a desire to hurt; motivated by spite):
spiteful, despiteful
WordNet sense 4 (having the nature of or resulting from malice):
malicious
From the ODE community, based on WordNet
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