backlog
n. countablen. a large amount of work or tasks that you have not finished yet and need to deal with. It usually builds up over time when you are too busy to keep up.
n. an accumulation of uncompleted tasks, work, or materials that must be processed. Refers to a volume of work that has exceeded the current capacity to finish it.
I have a huge backlog of emails to answer.
The hospital is working overtime to clear the backlog of elective surgeries that were postponed during the winter.
The sudden surge in consumer demand left the manufacturing plant with a significant backlog, forcing the management to implement a temporary freeze on new orders until the existing queue was cleared.
From back + log. 1680s; originally a large log at the back of a fire. Figurative sense from 1880s, meaning "something stored up for later use". Possibly influenced by logbook as well.
Commonly used with the verbs 'clear', 'tackle', or 'reduce'.