无稽之谈

Origin and story

The older expression 无稽之言 appears in the Zheng Ming chapter of the Xunzi (荀子), which urges caution about statements that cannot be checked. Here 稽 concerns examining or verifying something. The later form 无稽之谈 uses a different final word but preserves that concern with evidential support.

An attested use occurs in Ji Yun’s Yuewei Caotang Biji (閱微草堂筆記): after mentioning a story that someone had secretly kept a lookalike to die in his place and used the substitute to escape, Ji dismisses it as unsupported talk. That is an example of the idiom in use, not proof that Ji invented it. The expression rejects a claim for lacking a reliable basis, however entertaining it may sound.