Window dressing refers to actions taken or not taken prior to issuing financial statements in order to improve the appearance of the financial statements.
Here is an example of window dressing. A company operates throughout the year with a negative balance in its general ledger Cash account. (Its balance at the bank is positive due to the time it takes for its checks to clear its bank account.) Since the financial statements report the Cash amount appearing in its general ledger account, the financial statements would report a negative amount of Cash. However, the company does not want its December 31 balance sheet to report a negative cash balance, since it will be reviewed by many outsiders. To avoid reporting a negative cash balance the company does not make the payments for amounts that should be paid between December 26 and December 31. This postponement of payments allows its book amount of Cash to temporarily be a positive amount. Then on January 2, the company issues checks for all of the amounts that normally would have been paid at the end of December.