also: イマジナリ
na-adjective
Loanword from English; used as a na-adjective to describe something that exists only in the imagination, often in creative or psychological contexts.
彼女にはイマジナリーな友達がいる。
She has an imaginary friend.
その物語はイマジナリーな世界を舞台にして
The story is set in an imaginary world.