a bank account whose owner is identified by a number for the purpose of preserving anonymity.
an account identified only by a number, esp one in a Swiss bank that could contain funds illegally obtained
Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
Under this system, illicit foreign payments appeared to be going to an account opened in a personal or numbered account.