maybe you're not sure what "liar" means

Fleischer: On Iraq, ‘Saddam was the big liar.’

In an interview set to air over the weekend on CNN’s D. L. Hughley Breaks the News, Ari Fleischer admits that the Bush administration was wrong to claim that Saddam Hussein had WMD in the lead up to the Iraq war, but still insists that Saddam was at fault for the war. “Saddam was the big liar here,” Fleischer concludes:

FLEISCHER: We were wrong about weapons of mass destruction being in Iraq. […]

HUGHLEY: When you found out that you were wrong, how did that make you feel?

FLEISCHER: You just scratch your head and say, “How could we be wrong?” It wasn’t just us that thought he had weapons of mass destruction. The Egyptians thought it, the French thought it, the Germans thought it the United Nations thought it, Bill Clinton’s CIA though it. We all thought it. Saddam was the big liar here.

(Think Progress)
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Saddam said that he didn't have WMDs and it turns out he didn't have WMDs. How does that make him a liar?