otherworld; another world
Literary or poetic term for a world apart from the ordinary one; often implies a utopian or fantastical realm. Rare in modern everyday speech.
This garden feels like another world entirely.
His paintings evoke a separate, fantastical world.
From 別 (separate) + 乾坤 (heaven and earth, the universe). The compound literally means 'separate heaven and earth', i.e., a distinct world. The exact historical derivation is uncertain, but it follows classical Chinese-influenced word formation.