The Greek adjective ametanoētos (ἀμετανόητος) means "unrepentant" or "impenitent" — from a- (negative) + metanoeō (to repent, change one's mind). It describes the condition of a heart that refuses to turn from sin even in the face of God's patience and kindness. The word appears once in the New Testament (Romans 2:5) in Paul's indictment of those who presume on God's goodness while continuing in sin.
Paul's use of ametanoētos in Romans 2:5 is devastating: "But because of your hard and unrepentant heart you are storing up wrath for yourself on the day of wrath when God's righteous judgment will be revealed." The image is economic — every day of unrepentance is a day of accumulating wrath. God's "kindness, forbearance, and patience" (Romans 2:4) are designed to lead to repentance (metanoia), but when misread as divine indifference to sin, they become a false security that compounds judgment. This passage is a crucial counterweight to cheap grace: God's patience is not permissiveness. Ametanoētos is ultimately a self-inflicted condition — no external force keeps a person unrepentant except the hardness of their own will.