A backorder is an order held because stock has run out. On backorder, clear the backorders, a long backorder.
It differs from a cancellation, since the customer is still waiting and the seller is still committed, which is why a long backorder does more damage than a refusal. Suppliers fill them in the order received.
1nounbackorderAn order held because stock has run out.
“The sofa we wanted is on backorder and won't arrive until March.”
backorder is an order.
From back + order.
Etymology from Wiktionary, CC BY-SA