There are three Greek words used in the New Testament to denote repentance.
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).
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 (Psalms 119:128; Job 42:5,6; 2co 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 (Psalms 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 (Psalms 51:1; 130:4).
These dictionary topics are from M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition, published by Thomas Nelson, 1897. Public Domain, copy freely.
Easton, Matthew George. "Entry for 'Repentance'". "Easton's Bible Dictionary".