@Pandya, good finding. So here you yourself can see that it suggests "illusion", & not "non-existence". The meaning of "unreal" means, you and me chatting is not real. The meaning of "unworthy" means, the seriousness involved in our chatting is not worth. Our true nature is with Brahman, so whatever we do as Jeeva actually doesn't account or matter.
Do you feel that, you and me are not real?
1. If NO: Then MithyA doesn't mean "unreal"
2. If YES: Then everything is "unreal". That means, the meaning of "MithyA = unreal" is also "unreal"!