There are three Greek words used in the New Testament to denote repentance.
(1.) The verb metamelomai is used of a change of mind, such as to produce regret or even remorse on account of sin, but not necessarily a change of heart. This word is used with reference to the repentance of Judas (Matthew 27:3).
(2.) Metanoeo, meaning to change one's mind and purpose, as the result of after knowledge. This verb, with (3) the cognate noun metanoia, is used of true repentance, a change of mind and purpose and life, to which remission of sin is promised.
Evangelical repentance consists of (1) a true sense of one's own guilt and sinfulness; (2) an apprehension of God's mercy in Christ; (3) an actual hatred of sin (Psalm 119:128; Job 42:5, 6; 2 Corinthians 7:10) and turning from it to God; and (4) a persistent endeavour after a holy life in a walking with God in the way of his commandments.
The true penitent is conscious of guilt (Psalm 51:4, 9), of pollution (51:5, 7, 10), and of helplessness (51:11; 109:21, 22). Thus he apprehends himself to be just what God has always seen him to be and declares him to be. But repentance comprehends not only such a sense of sin, but also an apprehension of mercy, without which there can be no true repentance (Psalm 51:1; 130:4).