萍水相逢

idiom

a chance encounter between strangers; to meet by chance like drifting duckweed

This idiom uses the metaphor of duckweed (萍), which floats randomly on water, to describe a fleeting, coincidental meeting between people who were previously unacquainted. It often carries a poetic or slightly sentimental tone, implying the encounter is brief and lacks deep roots, like the duckweed. It is typically used in formal or literary contexts.