the truth will out1 SHOW/BE A SIGN OFused to say that it is difficult to hide a murder, the truth etc 谋杀案/真相等终将水落石出！ → murder/the truth etc will out! at out3(1)
2 old-fashionedTRUE used to say that even if you try to stop people from knowing something, they will find out in the end 真相终会大白的 → the truth will out at truth(6)