This is the 16938th most frequent Korean word.
상상한
"Imagined."
In this sentence, '상상한' is used as an adjective meaning 'imagined' to describe the noun '세상' (world).
나는 상상한 세상 속에서 산다.
I live in an imagined world.
Here, '상상한' is paired with '이야기' (story), indicating that the story was created in his imagination.
그가 상상한 이야기는 정말 흥미로웠다.
The story he imagined was really interesting.
In this context, '상상한' describes '이상' (ideals), referring to the concepts formed through imagination.