backlog
noun [ C, usually singular ]
uk/ˈbæklɒɡ/ usa large number of things you have to do or deal with that has increased over a period of time:
She has a three-week backlog of work.
a backlog of orders
a growing/huge backlog
catch up on/deal with/clear a backlog I need to catch up on my backlog of emails before I can start work.