It stands for the Current Account Deficit. In layman's terms, it occurs when an economy spends more on its imports from overseas than it receives for exports to other countries. E.g. if Australia is getting $150 for wheat, but still spending $450 for imports, it would be an economic loss as more of Australia's money is going overseas than it is getting back. It is not necessarily a bad thing, however. Look up a guy called Pitchford if you get the time.