Ar: naskh.
According to some Muslim commentators, more than 260 verses of the Quran have been abrogated. Others concede only 5 verses while others deny there is any abrogation. Thus, there is no general agreement as to what all the abrogated verses are. This can become a point of confusion as sometimes, these abrogated verses deals with matters of life and death. For example, most scholars believe that the stoning verse for adultery for married persons, which was once in the Qur'an, has been abrogated from recitation, but remains in effect in the Sharia.
The issue of abrogation is a very serious problem for the Qur'an and its claims for two reasons:
1. If the Qur'an is the actual Word of God, then it is eternal and, is thus incapable of change. The abrogation problem suggests that the Qur'an was created, and cannot be the uncreated Word of God.
2. If the Qur'an is the Word of God, it should be perfect and no verse can be superior to another.
This verse can cause quite a consternation. In the case of the Stoning Verse for example, there was no replacement (better or not). Neither was there any replacement for the Missing Bismillah, the Ibn Adam Verse, the Suckling Verse or the "Pleasing" Verse.
Detailed information and discussion on the topic of "Abrogation" can be found in these articles.
Every instance of abrogation is a problem for the doctrine of an
unchanging God and should equally trouble thinking Muslims. For
non-Muslims, however, the changing commands regarding the use of
violence against non-believers are certainly the most relevant: