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 (Matt. 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 (Ps. 119:128; Job 42:5, 6; 2
Cor. 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 (Ps. 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 (Ps. 51:1; 130:4).