yì异differentxiǎng想thinktiān天skykāi开open
To have a wild fantasy; to indulge in the wildest fancies; to be impractical.
Literal meaning
different (异) — think (想) — sky (天) — open (开)
Origin
A classical four-character phrase describing unrealistic or fanciful ideas.
Examples
Tā de jìhuà tài yì xiǎng tiān kāi le, gēnběn bù kěnéng shíxiàn.他的计划太异想天开了，根本不可能实现。
His plan is too far-fetched and impossible to realize.
Bié别yì异xiǎng想tiān天kāi开le了，hái还shì是jiǎo脚tà踏shí实dì地de地gōng工zuò作ba吧。
Stop daydreaming and work practically.
Usage & nuances
Used negatively to criticize someone's ideas as unrealistic or impractical.
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