1.
If someone is living in a make-believe world, they are pretending that things are better, different, or more exciting than they really are instead of facing up to reality.
...the glamorous make-believe world of show business...
N-UNCOUNT [ disapproval ]
2.
You use make-believe to refer to the activity involved when a child plays a game in which they pretend something, for example that they are someone else.
She used to play games of make-believe with her elder sister.
...his make-believe playmate.
N-UNCOUNT
3.
You use make-believe to describe things, for example in a play or film, that imitate or copy something real, but which are not what they appear to be.
The violence in those films was too unreal, it was make-believe...
ADJ