The Greek verb ekdikeō means to avenge, vindicate, or carry out justice — specifically to right a wrong on behalf of someone who has been harmed. Derived from dike (justice, right), it carries the sense of making justice 'go out' (ek-) — executing what is rightfully due. It can be used of human legal action and of God's eschatological judgment.
Ekdikeō is central to the theology of divine justice and patience. Luke 18:3 features the persistent widow crying 'Avenge me of my adversary' — and Jesus uses this to teach about prayer and God's certain justice. Romans 12:19 commands: 'Do not take revenge (ekdikeō)... for it is written: It is mine to avenge.' The prohibition on human vengeance rests precisely on the certainty of God's ekdikeō. Revelation 6:10 shows the martyrs crying for God to 'avenge our blood' — answered definitively in Revelation 18-19.