A crime consisting of having assets and using them without telling the Feds. Or possibly just having too much cash around. An excuse for Janet Reno to seize everything you own.

See Forfeiture Endangers American Rights.

For a less satirical definition, you may read the other writeups. But honestly, there are plenty of horror stories when it comes to money laundering, Big Brother aside.

In any event, according to the 1986 Money Laundering Act, legally, that is just what money laundering is--any unreported cash transaction greater than $10,000 dollars (or other large movements of assets) is a felony and may result in those assets being seized, even if no other crime is alleged, the sort of law you'd expect in Communist China.