Money Laundering
The international financial system is very complicated and it is very difficult to track illegal transactions.
It is therefore easy for criminals to deposit illegal money into legal bank accounts and move it through the financial system in a process known as money laundering.
To launder means to clean.
When money is laundered, dirty money or money gained from criminal activity is cleaned so that it looks like legal money.
It can then be used without drawing the attention of the police.