backlog
     n 1: 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)
     2: large log at the back of a hearth fire [syn: {log}]
     3: something kept back or saved for future use or a special
        purpose [syn: {reserve}, {stockpile}]
     v : accumulate and create a backlog
Source: WordNet® 2.0