I agree with Wikipedia's definition of the word, "repentance":
The doctrine of repentance as taught in the
Bible is a call to persons to make a radical turn from one way of life to another. The repentance (
metanoia) called for throughout the Bible is a summons to a personal, absolute and ultimate unconditional surrender to God as Sovereign. Though it includes sorrow and regret, it is more than that. It is a call to
conversion from self-love, self-trust, and self-assertion to obedient trust and self-commitment to now live for God and his purposes.
[2] It is a change of mind that involves a conscious turning away from wrong actions, attitudes and thoughts that conflict with a Godly lifestyle and biblical commands, and an intentional turning toward doing that which the Bible says pleases God. In repenting, one makes a complete change of direction (180° turn) toward God.
As for the etymology of the word, "repentance" - here's what I find online:
repent (v.)
c. 1300, "to feel such regret for sins or crimes as produces amendment of life," from Old French repentir (11c.), from re-, here probably an intensive prefix (see
re-), + Vulgar Latin *penitire "to regret," from Latin poenitire "make sorry," from poena (see
penal). The distinction between
regret (q.v.) and repent is made in many modern languages, but the differentiation is not present in older periods. Also from c. 1300 in Middle English and after in an impersonal reflexive sense, especially as (it) repenteth (me, him, etc.).
Furthermore, the Bible shows that repentance,, if real - shows evidence of it's taking place by the fruit or works that show in the person.
Luke 3:7-8
7 Then said he to the multitude that came forth to be baptized of him, O generation of vipers, who hath warned you to flee from the wrath to come?
8 Bring forth therefore fruits worthy of repentance, and begin not to say within yourselves, We have Abraham to our father: for I say unto you, That God is able of these stones to raise up children unto Abraham.
KJV
Matt 7:16-17
16 Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles?
17 Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit.
KJV
Luke 9:23-24
23 And he said to them all, If any man will come after me, let him deny himself, and take up his cross daily, and follow me.
24 For whosoever will save his life shall lose it: but whosoever will lose his life for my sake, the same shall save it.
KJV