verb (used with object), back·logged, back·log·ging.
verb (used without object), back·logged, back·log·ging.
Origin of backlog
1680s, "large log placed at the back of a fire," from back (adj.) + log (n.1). Figurative sense of "something stored up for later use" is first attested 1883, but this and the meaning "arrears of unfulfilled orders" (1932) might be from, or suggested by, log (n.2).