The Greek noun dike denotes justice as a principle, the execution of justice, or specifically the penalty/punishment imposed by justice. In classical Greek, Dike was the goddess of justice. In the New Testament it occurs in the context of divine retribution and the just execution of judgment — God's justice applied to wrongdoing.
The New Testament's use of dike reinforces that God's justice is real, inexorable, and personal. Sin has a penalty; that penalty must be paid. The cross is the supreme demonstration of dike: the just penalty for human sin was borne by the Son of God, satisfying divine justice while opening mercy to the guilty (Romans 3:26 — God is both just [dikaios] and the justifier). Those who persist in rejecting Christ will face eternal dike (Jude 7; 2 Thessalonians 1:9). Justice runs through the universe like bedrock.