不辞而别

bù cí ér bié

to leave without saying goodbye

Character by character

不bù
not

辞cí
take leave

而ér
and

别bié
part

他昨天不辞而别，大家都很担心。

He left yesterday without a word, and everyone's worried.

Tone: neutral.

Often hints at a sudden or hurt departure.

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