An "overdraft" refers to a financial situation where an individual or organization withdraws more money from their bank account than the account holds. Essentially, it is a form of short-term borrowing in which the bank allows the account holder to go into a negative balance. This can happen with checking accounts, and it incurs interest and fees as a result.
The term "overdraft" is formed from two components: "over," which means "beyond" or "above," and "draft," which refers to a withdrawal of money from an account. The word has been in use since at least the early 20th century.