expression, noun
dream within a dream; wildest dream; pie in the sky
Used for something so unlikely or ideal that it feels like a dream inside a dream. Often appears in phrases like 夢の夢だ or 夢の夢に終わる.
世界一周旅行なんて、私にとっては夢の夢だ。
A trip around the world is just a dream within a dream for me.
その計画は結局、夢の夢に終わった。
That plan ended up being nothing more than a pie in the sky.