Before we leave work each day, we make a backup of all the records we have entered into the computer that day.

backup 是由动词短语 back up 合并而成的名词。back 表示"后面、返回"，up 表示"向上、完全"，合起来表示"将数据复制保存到另一个地方作为备用"的意思，即"备份"。