Dictionary.net

a card (usually plastic) that enables the holder to withdraw money or to have the cost of purchases charged directly to the holder's bank account

A card issued by a bank that combines the functions of an ATM card and checks. A debit card can be used to withdraw cash at a bank like an ATM card, and it can also be used at stores to pay for goods and services in place of a check. Unlike a credit card, a debit card automatically withdraws money from your checking account at the time of the transaction. Debit cards are regulated by the Electronic Funds Transfer Act.

A card used to do cash transactions that is not a credit card. It is taken from the balance of the cardholder. If it is more than is available than it is denied. AKA asset card or payment card.