It is no surprise that a word that is as important to our eternal salvation as 'Repent' is should be afforded a tight and well defined vocabulary in both main Biblical languages. It is perhaps rather more interesting that the primary meaning shifts quite markedly between the two testaments and that the Bible very clearly emphasizes the change. The aim of this brief paper is to detail how this word is defined in both languages and then highlight the semantic shift from Old to New Testaments.
The dominant Hebrew word rendered 'repent' is nâcham (H5162). The word literally means 'to sigh' and can therefore be used to express a range of feelings in the area of regret or sorrow. It is rendered comfort(65), repent(39).
A very common Hebrew word which is rendered 'repent' on three occasions is shûb (H7725). The word means to turn back or away. It is usually rendered: return (396), again(245), turn(220), bring(111), back(70), come(30), restore(27) and many others. All three occasions it is rendered 'repent' it refers to the behavior that God wanted the captives in Babylon; especially with regard to their idolatry.
There is a Greek word that is directly equivalent to nâcham, it is metamellomai(G3338). It occurs on six occasions in the New Testament. The definition of the word according to Strong's is 'to care afterwards'. Biblically the defining occurrence is in Heb 7:21 when it is used as a Greek rendering of Psa 110:4 which gives us the equivalence to the Greek. The only other occasion this word is rendered 'repent' it refers to Paul's lack of remorse at having upset the Corinthians with a stern letter. Rendered as 'repented' the word is also used by the Lord in a parable, to describe the indifference of the religious elite to John and to describe the emotion of Judas subsequent to betraying Christ.
However the dominant Greek word rendered 'repent' in the New Testament, and the one immortalized in such phrases as 'Repent ye for the kingdom of heaven is at hand' is metanoeō (G3340). Strong's defines it to mean: 'think differently' and if you break it down into its' components it literally means: 'change how you exercise your mind'. On all thirty-four occasions it exists in the Greek it is rendered repent, repented or repenteth.
We thus see that in the Old Testament regret, remorse and repentance are all closely intertwined and that on only three occasions is a change of behavior mandated by the Hebrew word used. The Greek of the New Testament is fully capable of expressing this emotion but it only does so in contexts unrelated to the principle concept of Salvation. The repentance tied to Salvation (or entering the kingdom) is not emotional but cognitive: it demands our minds to be altered and conformed to a new pattern.
This does not, of course, imply that the realization of one's sin and the acceptance of the atoning blood of the Savior will be an unemotional moment. However it does strongly suggest that a heightened emotional state is not enough to presume that salvation has occurred. It is the changing of the mind of the individual which counts.