back order noun
plural ∼ -ders chiefly US, business : a product that has been ordered but not sent to the customer because it is not yet available [count] ▪ The book I want to buy is a back order and won't be shipped for three weeks. [noncount] ▪ The book I want to buy is on back order and won't be shipped for three weeks.
— back–or·der verb, back–or·ders; back–or·dered; back–or·der·ing [+ obj]
▪ The book I want to buy has been back-ordered and won't be shipped for three weeks.
▪ The book I want to buy has been back-ordered and won't be shipped for three weeks.
