Overdraft

[Sarah]

The act of overdrawing; also, the amount or sum overdrawn.

[Sarah]

The amount by which withdrawals exceed deposits, or the extension of credit by a lending institution to allow for such a situation.
PRETTY MUCH WHEN ONE OF THE BANK'S WORKERS IS STEALING YOUR MONEY.

[Sarah]

an amount of money that a customer with a bank account is temporarily allowed to owe to the bank, or the agreement that allows this:

[Dianne]

A deficit in a bank account caused by drawing more money than the account holds.