Definitions of blank cheque
a cheque (=a written order to pay) that has been signed but on which the amount is not stated
She gave a blank cheque to the cashier and asked him to fill in the amount.
when someone has given you either unlimited freedom to do what you want or unlimited money to spend, especially on a project, scheme, or plan etc
The Prime Minister gave a blank cheque to Nepal to come up with its own proposals.