From Longman Business Dictionarytestdecktest‧deck /ˈtestdek/ noun [countable]ACCOUNTINGCOMPUTING a computer program which is used to check a small amount of DATA (=information held by a computer). The results of the calculations are then compared with the results of calculations done by a person to make sure the computer is operating correctly. Testdecks are often used as part of an AUDITThe testdeck will reveal errors in the income and expenditure account operation.
