When an item is not immediately available for purchase or delivery, it is said to be on backorder. However, there are several synonyms that can be used to describe this situation. One alternative is the term "out of stock", which refers to a product or item that is currently unavailable due to high demand or low supply. Another synonym is "delayed shipment", which indicates that a product or item will be shipped later than expected due to unavailability. Additionally, the term "pre-order" is often used to describe products that are not yet available for purchase but can be reserved in advance. Employing different synonyms enables individuals to communicate more effectively about the status of an item or product.