"backlog" in the noun sense
an accumulation of jobs not done or materials not processed that are yet to be dealt with (especially unfilled customer orders for products or services)
the large log at the back of a hearth fire
3. reserve, backlog, stockpile
something kept back or saved for future use or a special purpose
"backlog" in the verb sense
accumulate and create a backlog
Source: WordNet® (An amazing lexical database of English)
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