fabricated dream; made-up dream
Refers to a dream that is not real, often used in literary or poetic contexts to describe something illusory or a dream that one knows is not true.
It was nothing more than a fabricated dream.
Compound of 空 (そら, 'empty, false') and 夢 (ゆめ, 'dream'). The exact historical derivation is uncertain, but the word is formed from these components to mean a dream that is not real.