If you have an overdraft, you have spent more money than you have in your bank account, and so you are in debt to the bank.
例句
When I left Cambridge I had a £10,000 overdraft...我离开剑桥时,透支了1万英镑。Her bank warned that unless she repaid the overdraft she could face legal action.银行警告她如果不偿还透支钱款,她将面临诉讼。
英汉词典释义
n.
透支, 透支额
An overdraft resulted when a 1000 cheque was drawn against only 900 in the account.当账户上只有900美元时你支取1000美元, 那就造成了透支。