an amount, usually 5-10% held back from the sum due to a contractor, for payment at a later date. The amount will be specified in the conditions of contract. Retentions are usually released on the basis of half at the issue of the certificate of practical completion, the remainder at the issue of the final certificate.

Amounts withheld from progress billings until final and satisfactory project completion

Portions of contracts that are not paid until all contract provisions are satisfied. Sometimes called holdbacks.