随风倒柳
suí​fēng​dǎo​liǔ

bending willow

随风倒柳 (隨風倒柳) suí​fēng​dǎo​liǔ
bending willow
literally, a willow tree that sways or bends in the direction of the wind
unprincipled
an idiom describing a person who has no fixed principles and shifts their position to follow the crowd or suit the current situation

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Definitions
CC-CEDICT