The definition of a back order is an order that will be sent out when the item(s) is restocked.
An example of a back order is an order on a pair of shoes that aren't coming in to the warehouse for a few weeks.
Back order means to place or deal with an order for items that aren't in stock yet.
An example of back order is to put in an order for party favors that will not be in the warehouse to ship until next week.
An order to be filled when stock is renewed.
To deal with as a back order.
To treat as a back order.