more than is usual, expected, or than exists already
额外的；附加的◆Breakfast is provided at no extra charge.
供应早餐，不另收费。◆The conference is going to be a lot of extra work.
这次会议将有很多额外的工作。◆They said they would need to borrow an extra $500 million.
他们说还要再借 5 亿元。