Real Dictionary

make believe in British English
pretended; feigned; sham
pretense; feigning
to pretend; act a part
to pretend; imagine
adjective: imitating or copying something real, but not what it appears to be
adjective: pretended; feigned; imaginary; made-up; unreal
modifier: of or relating to a fantasy, pretence, or unreality
noun: a fantasy, pretence, or unreality
noun: pretense, esp. of an innocent or playful kind; feigning; sham
verb: to pretend or enact a fantasy

make-believe
uncountable noun: 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.
uncountable noun: 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.