In the Quran Jesus (PBUH) foretold that a prophet called Ahmad will come after him. Why does the Quran say Ahmad and not Muhammad?

In the Quran Ahmad could be a name but it could also be a description. The word Ahmad in Arabic has a similar meaning to Muhammad. Muhammad means the one who is praised. Ahmad means the one who is more praiseworthy.

The origin has been traced by some who thought that Jesus (PBUH) spoke Armenic rather than Arabic. This reminds us that Jesus (PBUH) spoke another language. It was obvious to Muslim commentators that Jesus (PBUH) was talking about another prophet after him.