backlog
n (usu sing 通常作单数) accumulation of work or business not yet attended to 积压的工作; 待办的业务
a backlog of work, unanswered letters 积压的工作[待覆信件]
After the postal strike there was a huge backlog of undelivered mail. 邮政部门罢工以後, 大量邮件积压下来.
My dear friend, Mathilde. Let me tell you something. That necklace you borrowed from me wasn't a real diamond necklace. It wasn't valuable at all. The stones in the necklace were made of glass. It was worth five hundred francs at the most.