What is the definition of a "back order" in supply management?

A "back order" is defined as an order that cannot be filled at the current time due to insufficient stock. This situation arises when a customer places an order for a product that is temporarily out of stock, but the supplier intends to fulfill the order once the item becomes available again. This definition highlights the essential nature of back orders as they indicate a pause in the order fulfillment process rather than cancellation or completion.

In contrast, the other options describe different scenarios that do not align with the concept of a back order. For instance, an order that is filled at the current time due to available stock contradicts the premise of a back order. Moreover, a completed order ready for delivery speaks to successful fulfillment rather than an unresolved status. Lastly, an order that has been canceled represents a total cessation of the transaction rather than a deferral pending stock availability. Thus, option A precisely encapsulates the situation of a back order in supply management.