He's nothing but a liar and a fraud.

他只不过是个撒谎者和骗子。

《牛津词典》

But when a liar confesses, can you believe him?

但是当一个说谎者坦白时，你会相信他吗？

youdao

Yet ye have not known him; but I know him: and if I should say, I know him not, I shall be a liar like unto you: but I know him, and keep his saying.

我却认识他。 我若说不认识他，我就是说谎的，像你们一样，但我认识他，也遵守他的道。

youdao

This entrepreneur doesn't shade the truth because he's a liar but because he lives in a future of wonderful possibilities.

FORBES: Dark Side of American Optimism

He testified that he pounded on a table and told the suspect he was a liar, but he denied physically abusing him.

NPR: Retired Detective Defends Record In NYC Case

And of course Louise was always trying to make out that she could see them too, but she was such an awful liar that I never believed a word of it.

NPR: Excerpt: The Sherwood Ring