back·log 
(băklŏg′, -lôg′)
(băklŏg′, -lôg′)n.
1. A reserve supply or source.
2. An accumulation, especially of unfinished work or unfilled orders.
3. A large log at the back of a fire in a fireplace.
v. back·logged, back·log·ging, back·logs
v.tr.
To acquire (something) as a backlog.
v.intr.
To become a backlog; accumulate.